It'll sound very counter-intuitive, but when you first meet a night troll and you check to see if they are carrying a weapon, it's better to avoid targeting their weapon arm when they are found with cutlery. This is because they are restricted to the types of attack you can block with a shield as all creatures with a weapon default to strikes and bites. An unarmed night troll is much much more dangerous than one with cutlery since it now features a grab attack.
I think bites are nastier. With grabs, the RNG has a chance to make a grab that can't be turned into a lock or a pinch. If a bite connects, a creature can always start shaking. Hmm, is there a skill that specifically opposes Biter?
If you can ruin a creature's weapon arm, you can ruin their non-weapon arm first and leave them unable to grab. I think I remember having creatures swap hands instantly when I hit the one originally holding the weapon, but my memory's really cloudy on that one.
While the shield can block bites (which is a grab in of itself), I agree. As a grab using upper or lower limb may be released/readjusted/followed by a strike before the night troll transitions to joint lock, you can still destroy the limb or strike the neck to break grips, while a bite can only be broken with a kill shot to the head, and while you may score the kill, you may also be crippled as the bite still went through. So yeah, definitely nastier.
Versus biter? I think it's just powerleveled STR + legendary wrestling? Since you still need to go into the fight menu and select wrestling to try break the grip of the bite.
I continue to avoid targeting the weapon arm. Recently (for me) I've been using blunt weapons
targeting the neck to bruise the spinal tissue which disables all limbs reducing the night troll to just being able to bite. Even if you are dodging the bites, the bite still requires (for best result) a
single action dodge or block when under attack. That being said, the neck shot makes them much easier/faster to kill now.