I rechecked my tests results and i was wrong, it was same chance as with shield and w/o shield in terms of chance ranges, because it all was close to bash cap. Bash always has cap
. For example for leatherleaf sappling it is 80%.
Retested below cap, and yes shield ups bash via parry bonus.
So Zarth is right finally
And yes mounted state ups bash by like 5-10%, i think it is bonus mounted vs unmounted and if both are mounted this bonus does not apply.
And spears does not have additional bash bonus while mounted, it is just mounted bonus.