ok, first off knights of the round DOES NOT give temp invincibility, the regen is around 10hp per tick
the shield does 10x damage for shield bash and gives a AoE stun effect, so if i had it my normal shield bash is 21, i would do 210 damage, and its classified as a type one shield meaning it will go off a lot (if you have a high enough shield skill) but doesnt reduce as much damage as a type 4 shield