Sniper is not really OP. Sniper takes many fully charged arrows to kill diamond gear (not counting regen, it's at least 9 against OP warrior, 12 against OP beast), assuming he consistently lands hits within that short time. On average, that's about 17% of the archer's quiver gone. Also, arrows aren't infinite unless the archer does /kill or buys 3 at a time from the shop.
Sniper is the weakest kit in melee combat unless he uses traps. Just strafe the bowspammer and you'll out-DPS him thanks to your mobility and his slow attack rate.
To OP, dodging arrows means the arrow deals ZERO damage to both your armor and you. Better that than to use the shield since shield takes 1.5 seconds to start blocking.