There's always been rumors of being able to kill bosses with Megid or Hell weapons, but as far as I know, they are all immune to the effect, as well Arrest, Demons and such, otherwise bosses would be too easy.
I believe that the odds of a weapon having Hit ( or any other specific %) don't change by location, however the odds of getting higher percent do, so while for example a DoB from Forest 1 COULD have high hit, statistically a DoB from Ruins 3 has a better chance of having higher hit. But in no...
I agree with Ade, as it is, mind mats are worth less than 1/10 of a pd, and power mats are well on there way there. Not that many mats are reset, id imagine, it's something to keep them worth even picking up.
Many old version glitches and tricks were fixed by the same virtue of being a server-side game, rather than a client-side game that connected to a server; others including item duplication, telepiping rare spawns, etc