That's a tricky one, not a lot to go off there, but if it was mine, I would use the regiment prefix as a reason to use an actual military rank as part of the name, and then either his pet name or something that sounds a bit like his dad's name.
Lieutenant Aragam ??
Black Brigadier ??
Colonel ........... ??
Or a word I can think of that is a bit like Aragon and Shanay put together is Shenanigans LOL