Two options, one boring, one that sounds sweet to me.
1) It's really good at looking like other warforged. It can pass off as a dock worker warforged, a cook warforged etc. Give it that Hitman vibe. Meh.
2) It's like a replicant or the T-1000, has a skin layer and understands some of the basics of displaying humanoid emotions. It can pass as most human like things, but will sometimes struggle with things like empathy. I'm sold (Blade Runner//Cyberpunk biases aside).
Or, if you are going for silly, it could be something similar to Chicken Boo from Animaniacs, or Sir Bearington from 4chan.