Sorry, everyone was only looking at half the mechanic for that damage boost. The system that checks whether enemies are near you does stack but the math coming back does not. Thus having two effects with this buff will not increase your damage output but will increase the reliability of that damage boost (though it'll be negligible in most real cases). IF, hypothetically, a new item had this effect but at a different value - say 10% per enemy instead of 5% - that would stack.
As for other effects stacking or not this is mostly a case by case basis.
So, just to clarify, what you are saying is that the mechanic for counting enemies around you stacks (meaning each enemy is essentially counted twice), but the actual damage bonus is only counted once (granted that the two items have identical bonuses)? Furthermore, if the effects are not itentical (your theoretical 10% masterwork), then both functions stack?
Quick math:
Example (Single Masterwork):
- Masterwork: 5% damage for each enemy within 8 meters.
- Weapon base damage 100 (nice even number).
- 3 enemies within 8 meters.
100 base * [1 + 3 * 0.05] = 115 damage
Example 2 (Stacked Identical Masterwork):
- Masterwork (x2): 5% damage for each enemy in 8 meters.
- Weapon base damage 100 (nice even number).
- 3 enemies within 8 meters.
100 base * [1 + 6 * 0.05] = 130 damage
Theoretical Example 3 (Stacked Similar Masterwork):
- Masterwork: 5% damage for each enemy in 8 meters *and* 10% damage for each enemy in 8 meters.
- Weapon base damage 100 (nice even number).
- 3 enemies within 8 meters.
100 base * [1 + 6 * (0.05 + 0.15)] = 190 damage
Does that sound right? Also, is this damage bonus counted as an Attack bonus (just like +Attack %)?