I don't think it will impact his defense much at all. I do, however, actually think it could help him offensively.
As for the hats, I always hated the Tomahawk A hats they trotted out with the Sunday red jerseys...but I actually really liked the tomahawk by itself. Not as any kind of primary hat they would wear during the season, but I would have bought one. The lower-case 'a' hats are cool, too, but they've had variations of those for a while.