I spent the whole night yesterday fighting the first boss (the one you're supposed to die to) restarting and fighting him again. But I did it.
You could safely hit him with magic, but you only had 12 casts and if you managed to hit each one (not miss or have it blocked) it would add up to 1,008 damage, which meant you had 1,592 HP left to get through with the short sword which has no range and deals abyssal damage (takes 33 two-handed hits).
Out of the "starting bosses/enemies you're supposed to die to" I think this is the hardest one, since he's so ****ing fast, he can reach across half the map, and any minor frame rate hick-up or him getting his weapons bounced off the wall will screw you over. Sure the Asylum Demon takes a long time to kill bare-handed, but you can do it reliably. This guy I still feel that I need multiple tries on.