Originally posted by Honorable_D:

They have like 10 HP.

When you see them come towards you start moving towards them and parry shield at the last moment while still holding forward. Then, if you did it right you'll be in melee swing range to 1-shot them.

They are there to keep people in Troll armor out of the Plains.

Except troll armor works just fine in the plains or any other area or boss as long as you know what you are doing.