Was the evil Archer Tommy's Dad
? I knew it wasn't Tommy, and the dark archer thing reminded me of Merlyn, but I didn't recongnise the guy when he took off the mask at the end, although I was sure that I was supposed to (even though Tommy's Dad has had, what, two scenes in the whole series so far?).
You must of missed some episodes. He has been in a lot more episodes than 2. His screen time has been slowly building to longer and more scenes as time has gone on. Tommy and the father had a scene together which confirmed their relationship.