>.< Bastard Sword you Bastard!!

Apperently my knowledge about swords is zero :( Bought two bastard swords for my shadow and expected some big numbers, but somehow the opposite happend and the damage output dropped drastically.
My shadow used two rapiers and did on average 300-400 dmg on most opponents, with bastard swords its about 140-300 dmg. I tryed everything...low activity...high activity...low bloodlust...high bloodlust....and anything in between and any fighting style.
Does anybody have a quick instruction for retards, so I can comprehend it or any good explanation why?

The shadow is max agi (306) and some chi/pres. does the bastard sword benefit from higher str as the main damage source? I never had any problems with the other swords, only the bastard.

First of all I doubt any of my gladiators has ever used bastard sword so I don’t have any first hand experience with weapon in question. I have understood that heavier blades don’t get their damage from agility alone but strength also affects their damage (and same other way around with tomahawks and pole arms). As heaviest sword from blades family I highly doubt that bs’s damage is based on agility alone considering their significant weight.