Arming sword is shorter with lower damage.
historically arming swords were excellent at penetrating mail as it was the most common armour of the time.
I suggest an increase in stab damage to 26p. (I would prefer 27 but that is out of line with its type of sword)
It will be worse than side sword in every way but it is cheaper and will make it a viable option for the frugal player. At the moment it is inferior to other mid tier swords and needs a solid buff.