Unholy weapons can't be weapon broke period. Iron grip doesn't matter

An AP with iron grip cannot be disarmed, fumbled, have their unholy stripped, hooked, entrapped, or offhanded. Iron grip can, however, be dispelled, at least until the point where they have the control that makes it undispellable.

To the best of my knowelege, unholy blessing a weapon strips it of it's stats, not it's progs. This is why the titanium spear is popular amongst spear wielding aps

I think leeching a weapon is one-for-one, but haven't used it enough or been attentive enough when doing so to be sure.