Checkout out my other Hyper Light Drifter Videos.
http://www.youtube.com/watch?v=yV6oC4EMvOQ
http://www.youtube.com/watch?v=H8_oZ7vweeA
Summary:
Dash Stab:
Deals 1 damage to large enemies and bosses, and 2-3 damage to small enemies.
Against large enemies and bosses dash stab is not very effective.
Parry Slash:
Deals 2 damage normally, but if timed correctly the initial hitbox of your sword can add an additional damage to the attack.
Effective way to reposition behind enemies and bosses or get out of corners. Effective at taking out multiple enemies and avoiding attacks by going through enemies.
In my opinion parry slash is much more effective early on and and is usable in most situations. Dash stab has good utility in the late game.
