The blaze orange hat probably isn't a bad idea. I don't know how it is on the AT, but in southwest Ohio I sometimes hear local hunters talk about taking "sound shots," as in:

Hunter 1: "Did you get any deer today?"

Hunter 2: "Naw, but I heard something moving up on the ridge, so I took a sound shot."

As far as carrying a larger knife - remember the old saying about bringing a knife to a gun fight?

I know, that's not a lot of help. I have a friend who hiked the trail a couple of years ago, passing through a few hunting seasons in various states. He never had any trouble or unfriendly encounters with hunters, though he did wear a blaze orange stocking cap or hung a brightly-colored flag on his pack.

My own advice, based on sharing trails with hunters in Ohio and Kentucky, is to remember that, for the most part, they're as serious about their pastime as we are about ours. Even if you abhor the idea of hunting (I don't; I just never had any relatives who hunted), treat them with respect and they'll probably reciprocate. As soon as you see one, quit talking (unless you're effectively invisible to him/her, then keep talking) so you don't scare the game away. As you pass by, ask in a low voice how they're doing, or otherwise chat for a few moments if the hunter seems so inclined. (Most hunters I've met are quite friendly.) If you've been talking or otherwise making lots of noise as you walk the trail, and don't see the hunter until you round the corner on the trail, quietly apologize and explain you didn't know anyone was hunting here. Most hunters will normally acknowledge the apology graciously (though there are jerk hunters, just like there are jerk hikers.)