I'm looking for feats that I can take to improve my mounts combat features. AC, attack and damage are the big ones.
Feats you can take, or your mount can take? What class is your character?
Feats I can take. Let's say I'm an inquisitor. My mount is specifically not my animal companion. I want this to help out any mount I ride.
Trick Riding is the only other feat I can recommend beyond Grandlounge's suggestions. You do not have very many options when the mount isn't tied to a class feature.
My mount is specifically not my animal companion. I want this to help out any mount I ride.
Save on the feats and cash the mount out for flying boots or a rug.
-- You're poor 2HD animal is just going to die in a fireball or a trap at some point, and every nickel you're spending on the thing now (saddles, barding, healing, etc) is an accumulating waste that you'll wish you had back at the point you're finally dragged into the realization that it's impossible to keep it alive.
If you're really insistent, then Mounted Combat + scale barding (non-magical) on a heavy horse trained for war. When you finally upgrade to boots (or whatever), you're only out 200 for barding and the cost of retraining the feat.
Also: it's not particularly expensive (unless your GM is a stickler for keeping track of your feed bills) to own a string of ordinary horses and just hop on a fresh one whenever one gets killed.