In pvp once u get ur charges u should release them straight away......so when ur that close to get ur charges might as well just release them rather than run away and kick u know where im at.....

Assassins are very fragile and dont have much life so for me i went as low stats as i can but not too low and i put the rest into vitality......u can probably use Wake of Fire or Lightning Sentry at level one and once they get hit with one of them u can use mind blast to stun them and u can df in or use ur bow to pump sum arrows in em....