Ok, well I was bored with my blitz so I was using my voltedge and leviathan on phase 1 vanaduke.
According to the wiki, the levi and volty should do the SAME dmg on the first 2 hits but then the volty should do more than the levi on the 3rd hit.
What I found was the volty did more dmg on every hit.
The damage was (with poison applied and max dmg (snarby shield + 2x sword dmg trinks):
Levi:301,301,369
Volty:344,344,463
I am too lazy to go and test stuff...
The wiki says he is only weak to piercing on 1,3,5, so why is the volty doing more dmg?
*I would also like to add that I know these are not the best swords for phase 1,3,5. This is purely theoretical.*
Check damage tables. On neutral targets, both weapons should have same damage, but the rbandish has a better 3rd hit.
It may have somethign to do with your damage bonuses you may have and Vana's weird defenses.
http://wiki.spiralknights.com/Voltedge
http://wiki.spiralknights.com/Leviathan_Blade