In my opinion, I would prefer lash. Since it actually stuns the opponent for an amount of time. I would rather have psychic binding in pve when you are low on hp and mobs are going for you. Some people use psychic binding for fun in pvp, some find it useful. Well, it can be useful when your lash misses and you have to slow down the opponent when you're low on hp or so. So yeah. I would prefer using lash