Feandal is good for sleath, especially if you don't give him heavy armor which he's not rated for. If all he has equipped is a bow, he tends hang back, so to make a range bow attack. He'll use no magic, so no noise from casting a flesh spell. He's also available to anyone at any point in the game (i.e. you don't have to join anything to get him--just do his favor). He's a ow level NPC, but I've used him with characters up to level 50 or so and have had no issues in terms of him dying or not being able to handle enemies. He IS however very vulnerable to your attacks.