Fun fact: the correct way of stabbing w/ a katana requires the wielder to turn the blade completely sideways prior to thrusting. The actual animation used, w/ the blade pointed up and to the right, is not entirely accurate.
Proposal: buff the stab by 2 as suggested by OP, but implement shorter, possibly slower, yet more historically accurate stabbing animation, w/ flat of the blade held completely parallel to the ground. This will appease weaboos and non weaboo's alike.