For those particular cards, as with the vast majority of enhancements, they trigger upon being played in battle. The only time an enhancement or character's special ability isn't immediately played is when the ability has a delayed trigger (for example, when X happens, do Y). So if either of Ishbibenob's weapons are already attached to an evil character, when that evil character enters battle resolve the evil character's SA first, then the weapon's; or if the weapon is played from hand during battle, immediately resolve the ability.
