Ahh, I didn't think of make_corpse
You might want to take a look at instead making it so that when the object is created it gets the bonus
By this do you mean when the mob is reset with the weapon?
As far as equipment, I mean that I'm unsure on how to check the dropped item isn't something like a potion/projectile/etc so it doesn't mess with values on objects it shouldn't (i.e. anything which isn't worn)
On a side note relative to this topic;
Another idea i may look into is some sort of 'drop table'; in which you can define a number of item vnums a mob has a chance to drop. It would have to list the vnums of the object along with their percentage change of dropping, then on make_corpse a function to stuff the corpse with the loot. This could also manage the Tiering of the weapons/armor too.