to put it bluntly
stab:
give a charge option to the katana stab. the more you rightclick and hold the more powerful the damage becomes
a quick stab by just pressing the rightclick will deal 70 damage,
holding the rightclick for 1 second deals 85 damage,
holding the rightclick 2 seconds will deal 100 damage,
holding the rightclick 2.5-3 seconds will deal 110-115 damage
(i’d recommend that, time and damage should change depending on weapon performance)
stab can be charged while sprinting, and when being used by phantom, starting the charge will de-cloak him if he is invisible.
slash:
change the slash damage to 50-55 (and increase the range or attack speed if under powered)
give phantom a slight speed buff to balance the merc , hopefully this will make phantom more maneuverable to make up for the lack of damage, and will give a higher TTK time to the katana, allowing more reaction time to the opponent,
this will hopefully also discourage players from camping and spamming stab to get quick kills on low health mercs, all the while still being a deadly weapon in the hands of a experienced player