Having "investigated" Sir Boil, you are sent after Sir Mash. Sir Mash is found across the bridge from Sir Boil. Just head across it and up the stairs. You will find him having set up a small camp just to the left of the walkway.
Having found Sir Mash head on over to his tent:
He takes great offense to this and attacks you. Once again, he is armored and a Knight so handle him appropriately.