item_damage Tag #2093

I need a tag to get the extra damagean item itself provides.
By this, I mean that I don't want to calculate strength potions, weakness potions or the entity itself's damage. Just the damage from the item.

This way, if I give a diamond sword to a zombie with 10 attack damage, a skeleton and a player with a weakness potion, the tag will always output 7.
Basically a weapon_damage, but it only calculates the item and not the entity's data