I like Hawk as a Transformed Dragon, but think Spenser should be a human. Explaining his prowess by a more supernatural background almost diminishes his grandeur as a man of honor overcoming the world around him. I'd go with a standard P.I. or even Big Bruiser with high Guns and Martial Arts (Boxing, of course). Hair Trigger Neck Hairs is a definite, too, considering how often he just happens not to get his brains blown out. 

Hawk is a more enigmatic figure, so having him as a T.D. is cool, and I'd agree that he's benn around a long time. If we forewent the Transformed aspect, though, say for a non-secret war game, he could be either an Ex-Special Forces or Killer (with heightened HTH skills, of course) or, again, Big Bruiser (both these guys are large, and they both take huge amounts of punishment and keep going). 

Either way, as a PI, Spenser could have Path of the Sharpened Scales, specifically based around Boxing. 

Hawk would just be the God of Gunfire. 

I experimented, and by no means are my versions of Hawk and Spenser Canon. 

What's that, Cheddar Cheese? Not Cannon, the detective? Canon as in liturgical canon? 

Oh. 

Never mind. 

Best, 

Mr. Timily Litella