So me and my friend Michael have been debating all night to know which boss is harder to beat.

Sephiroth in Kingdom Hearts 2
Or
The Final Boss in Dark Souls.

Now we all know that Dark Souls is overall a more difficult game. But I'm not asking how hard the games are, I'm asking how difficult the bosses are.
Please note that the sephiroth I'm talking about is the one from Kingdom Hearts 2, not him in Final Fantasy 7. My friend and i couldn't come up with an agreement, so i decided to take it up with the professionals, a.k.a. you guys.
Neither me or Michael have experienced both games, which is why we're biased toward our own games. So I'm looking for some unbiased people who went up against both bosses to come up with an accurate answer. Good luck!

Doesn't this depend on which game you're better at playing?

KH1's Sephiroth is infinitely harder than KH2's.

Quote from _Ai_

KH1's Sephiroth is infinitely harder than KH2's.

Don't you fight him in that arena place?

I have had the luck to play both, so this is what I think

About Sephiroth
-in Kingdom Hearts 1, Sephiroth was my nightmare, together with the optional last bosses from Aladdin's and Peter Pan's world: he had almost instant cast times for his flaming pillars and his sword attacks (and both had horryfing reach) and you couldn't get away from him or he would insta-kill you. However, if you could read his rythm, he was quite mechanical to fight (I remember it was mostly about parrying when a certain range was reached, but I'm not sure)
-About Sephiroth in Kingdom Hearts 2, he is way easier: you have unlimited casts of heal, restricted only by the time it takes for the mana bar to replenish and the improved parry/chain-combo system helps you a lot. The only things he has more powerful than before are his insta-gib (he flies while doing it, making him difficult to catch unless you have the jump/double jump upgrades at maximum) and more health, forcing you to not make mistake for a long time. However, even his insta-gib here is not a problem as long as you have elixirs on quick-cast (if this was its name)

About Gwyn (this is the last boss' name in Dark Souls)
-Gwyn has some characteristics that make him extremely frustrating to beat if you try to approach him under conventional ways: unlimited-like stamina, fast attacks, high reach and (obviously) tons of damage make it impossible to block all his attacks, retaliate in any possible way and especially healing (if you can't hide behind a pillar before healing, you're kinda dead)
-However, he can be easily dispatched if you have some experience about the game
All of his attacks (except the grab, the kick and the lightning) deal fire dmg and just before fighting him you get the chance to pick one of the best armors against fire. Also, they can all be parried and reposted, making the fight more of a game-mechanics-check-point if you learn his timings. Also, if you fulfill Solaire's quest by getting the second ending (it can be achieved either by entering a covenant and reaching a certain rank or by using a specific spell in a specific place) you can summon him to help you by tanking most of his attacks
-The ways I wrote up here, though, are mainly used by those who did their homeworks so I'm not pretty sure if they can be used as weights on the bilance

Also, some other points

-Sephiroth is still considered the strongest boss in Kingdom Hearts 2 (in Kingdom Hearts 1 the strongest was Possessed Riku (in effects, the number of swearings I did while fighting him were less than Sephiroth first-time ones))
-Even if approached in a conventional way, Gwyn is not the strongest boss: the strongest boss is Dark Souls is the Four Kings, especially in NG+

My last point would be this
From one side, even though KH2 Sephiroth is easier than KH1 one, he's still a pain in the ass to deal with, as the minimum mistake can force you to start over
From the other, Gwyn is a 50/50 boss: if you approach him under conventional ways, he's extremely difficult and frustrating to beat (even more than other normal bosses in the game); if you approach him with knowledge and a certain degree of skill, he's quite easy

Said this, I think Sephiroth is harder than Gwyn

Quote from DiPi

I have had the luck to play both, so this is what I think

About Sephiroth
-in Kingdom Hearts 1, Sephiroth was my nightmare, together with the optional last bosses from Aladdin's and Peter Pan's world: he had almost instant cast times for his flaming pillars and his sword attacks (and both had horryfing reach) and you couldn't get away from him or he would insta-kill you. However, if you could read his rythm, he was quite mechanical to fight (I remember it was mostly about parrying when a certain range was reached, but I'm not sure)
-About Sephiroth in Kingdom Hearts 2, he is way easier: you have unlimited casts of heal, restricted only by the time it takes for the mana bar to replenish and the improved parry/chain-combo system helps you a lot. The only things he has more powerful than before are his insta-gib (he flies while doing it, making him difficult to catch unless you had the jump/double jump upgrades at maximum) and more health, forcing you to not make mistake for a long time. However, even his insta-gib here is not a problem as long as you have elixirs on quick-cast (if this was its name)

I'm Pretty sure that in KH2 Sephiroth also attacks using Fire pillars and a variety of sword lunges. Also didn't majority of sephiroths moves get you down to a one hit health? Or at least 2-4 hits would.
Anywho i would say the most annoying thing about Sephiroth in KH2 is the amount of Hp he has rather than his attacks

I'll be honest here, I haven't played both of them in a loooooong time. One thing that I remember is that I beat KH2 Sephiroth several times, just for fun while I can't beat KH1's boss at all. Not even half his health.

I think KH2's Sephiroth has easier to read attacks, also the special action you can take (I vaguely remember that you can press triangle or some shit to dodge his attacks) and yeah, infinite heals. I think you can dodge the fire pillars via gliding all over the place.

Considering I didn't even beat KH1's Seph I don't remember anything about him aside from I can't land a hit on him because I was too busy dodgerolling.

Quote from Lamitrov

Don't you fight him in that arena place?

Yeah. Hercules's place.

I'm a Dark Souls fan but Sephy definitely has this. Gwyn, despite his relentless assault and powerful weapons, is limited to a physical moveset and doesn't have far-range attacks aside from a leap.

Quote from DiPi

Four Kings

Don't you mean Bed of Chaos? That boss was BS artificial difficulty all over. On a more serious note, O&S are fairer bosses that's still challenging.

Quote from GuardianTempest

I'm a Dark Souls fan but Sephy definitely has this. Gwyn, despite his relentless assault and powerful weapons, is limited to a physical moveset and doesn't have far-range attacks aside from a leap.

Don't you mean Bed of Chaos? That boss was BS artificial difficulty all over. On a more serious note, O&S are fairer bosses that's still challenging.

Lol, Bed of Chaos?
You mean the only boss you can win by just having a fast roll and 0 weapons? Or that you can easily dispatch with 2 arrows and a jump?
I admit he has the possibility to insta-kill you by dropping you down the platfroms, but he's kinda mechanical and easy to beat. Also, even if you lose, you do not have to start all over

About Ornstein and Smough, you can summon Solaire which greatly helps you in it. Also, even without summons they can't be compared to the 4 Kings. Especially in NG+

Doing a bit of research, I have to agree with you. I don't know how much help Beatrice would be in that fight (compared to Solaire's contributions).

I think it's been like 4ish years since I played KH2 so I can't remember much about it. I'm pretty sure I defeated all the bosses in the game so I must have beat Sephiroth. I do remember that I found the whole game a lot easier than KH1 though.

Dark souls I didn't actually find too difficult, I think I got through my first playthrough in under a week and I killed Gwyn on like my 5th try (with the help of 1 other player) having an extra person made it super easy as we both had a lot of time to drink potions and stuff. But I think I could only get him down to a quarter health by myself. As for the four kings they were quite easy I think I got them on my second or third try I think with no helpers (first try I forgot to put on the ring that lets you go in the abyss and died lol).

Quote from XaioShadow

Dark souls I didn't actually find too difficult, I think I got through my first playthrough in under a week and I killed Gwyn on like my 5th try (with the help of 1 other player) having an extra person made it super easy as we both had a lot of time to drink potions and stuff. But I think I could only get him down to a quarter health by myself. As for the four kings they were quite easy I think I got them on my second or third try I think with no helpers (first try I forgot to put on the ring that lets you go in the abyss and died lol).

Let me guess, you still did not face them in NG+, right?
In NG+ they have basically double health and a shit load of damage, making it extremely difficult to follow their rythm unless you researched them beforehand
If you actually beat them easily in NG+, though, I think I'm gonna recognize you as my lord and saviour

Also, contrary to what people may think, to fight the 4 kings without AI helpers is way better than with them: the only one you can get there is Witch Beatrice, who does not help at all and only makes it harder (if you summon somebody to help, bosses take reduced dmg)

I think I got half way through my NG+ playthrough before I got bored and played something else so no I didn't fight the four kings again. Although I am tempted to go try it now. And I knew about the reduced damage thing but its still easier because you get time to take potions while the boss is attacking the other player(s)

Quote from XaioShadow

I didn't fight the four kings again

I'm gonna recognize you as a filthy casual then

Quote from DiPi

I'm gonna recognize you as a filthy casual then

woah, hey >_> I had other games to play. And I beat the game once anyway so I figured that was enough.