I've posted this already in another topic. With the Mag7/Hugemod mod there's a 43b rune axe, wich maybe for a mistake deals bash damage (and yes it's bash, as it knocks foes unconscious), so I was able to test on many battles my 42c axe vs this 43b axe.
In theory, as bash halves armor, the 43b should deal at least 25-50% damage more than the 42c. In pratice it deals less damage against foes, expecially the armored ones, regardless of +X% speed bonuses.
Usually is 55-70 (unarmored) 40-50 (armored) for the 42c weapon, vs a mere 45-60 (unarmored) 30-40 (armored) for the 43b weapon, tested on foot while inside a river filled with dark knights or mountain bandits (they're so clumped they can't move, so speed bonus rarely is higher than +10%).
I've also noticed that the bash weapon gains less bonus when charging at full horse speed.
Those tests were performed with a 220+ wp skill/18 str/18 agi/6 pow strike char.