Well, my latest attempt to beat the game in vanilla has been thwarted. Not by my character's death, oh no, rather it was because my character has had... THIS... happen to him: Inverse buff integration. I was in a monster zoo, and the sight quirks of it allowed me to keep on fighting even though I was getting bombarded with curses of darkness. The result: either by leveling up or clearing the zoo, not sure which, probably the former, I was granted these stats. I'm particularly referring to the nimbleness, sight range, and trap sight radius. My character is no longer a legit character, and any victory I have with him will be empty Also, fun fact, the 21 sight radius doesn't actually seem to do anything; I still have the same sight radius I had at zero.
your problem is that you're using a melee build. and vanilla melee builds are very weak towards the end of the game. try a mage.