I blessed the opponent's vampire dagger 2 times, the used both sader's endow on it. Saders didn't pick up what they should have.
Confirmed. It's more of an error in blessing though.
When you bless an opponent's (has to be opponent's) dagger, only its "current" Attack and HP go up. This seems to be only for blessing though; I tried SoW, and both its current and full attack went up.