Spellweaver and lightning runes
Edit: I downloaded a logger to do further testing.
The log shows that Spellweaver with 2 lightning runes does indeed do 21 total lightning damage. It also shows the enemy health being reduced by an amount equal to the base hit +21.
I believe this puts spellweaver as one of the higher DPS options despite being only a tier 6 weapon. Very nice for an arcane warrior build like the one I've been running it on.
So I noticed that when you stack lightning runes on spellweaver it seems to double count the effect. Here is what my testing showed:
Spellweaver + no runes: base damage number + 3 lightning damage
Spellweaver + GM fire and frost runes: base + 3 lightning + 5 fire + 5 frost
Spellweaver + GM lightning rune: base + 8 lightning + 5 lightning
Spellweaver + GM and master lightning runes: base + 12 lightning + 5 lightning + 4 lightning
So visually at least it seems that Spellweaver double dips on lightning damage. My question is if this is purely a visual bug, or if it's actually doing 21 lightning damage per swing. I don't have a way to check, I'm hoping someone else will have some insight.