Alright so, did some looking, please forgive me if i get something wrong i've never read berserk
Dragon Slayer specifically negates regeneration by causing wounds to constantly reopen, due to the soul being destroyed and that not being healed or smth like that
but they still
do close at first, they just reopen after a time, and apparently the stronger the healing magic the slower the wound is to reopen. Now, hybrids' healing factors are insane, denji has actively come back from the dead after being reduced to a head and having his body chopped up into pieces. if he was continuously drinking blood,
like the blood that would be constantly falling off guts due to the berserker armor, i think he would be able to keep himself together, at least until he stopped getting a constant supply and immediately fell apart again from all the wounds reopening at once.
quote from the notes on guts' page:
Notes:
- While there are claims that Dragon Slayer negates durability by attacking the soul, this is not true, nor are claims it outright possesses a busted degree of regeneration negation (this argument commonly phrased as something to the effect of "Dragon Slayer kills with a scratch"). Its power is more along the lines of creating wounds that will never fully recover, and even if healed or regenerated, they will open up again. This isn't full-blown regeneration negation but will function as such when it comes to more debilitating injuries.