I know im late, but i figure i'd chip in.
My biggest problem with bears is that on top of dealing some 10-12 damage, they also attack incredibly fast, and half the time with no attack animation.
I use longswords from the combat overhaul mod, and i've been trying to parry them, and half the time theres no animation, i just eat damage.
i would assume the same problem exists for players trying to use shields.
My honest opinion? just install "yet another bear patch" by chumber.