Griffins usually scurry away when you attack. Weaverns will put up a fight, but usually nothing a gentleman warrior cannot handle. Saracens, on the other hand, will charge in packs if spooked. They are very protective of their young and suspicious of humans, so beware of them. If it's saracens, you should probably bring a posse with you, and come heavily armed.
Romans are, for the most part, as weak and wimpish as Cornish knights.
Giants are difficult to drive out, but they can usually be outwitted.