For starters, put that charisma back into Strength. While a lot of paladin abilities key off charisma, you're spending most of your time vigorously applying your weapon on your enemy, the to hit and damage bonuses would serve far better. As it is you're getting merely 1 more damage out of Double Slice, when if you swapped your Str with Cha you will be getting 2 AND the to-hit you badly need.
Secondly, ditch the exotic weapon proficiency, if you're mounted(see next question) you can use a lance one handed, or just a plain scimitar(the higher crit range works well with the later critical feats). Swap it for Power Attack instead, it works even for off hand attacks, and if your strength is swapped with charisma you should be able to hit even when power attacking.
Thirdly, what is the campaign premise?
Overland or dungeon crawl? The new mount is somewhat better(its animal companion based), but it does rely on being able to well...ride.
Fourth, clarify with your DM if Double Slice's benefits carry over to power attacking as well, if not you might want to replace it(+2 damage to a secondary attack isn't really worth it on its own). Given your higher than usual Dex you might find a use for Combat Reflexes(opportunity attacks = more crits = more extra shield bashes).
Fifth, check if you can afford a keen weapon. No sense throwing a feat slot after it when you could instead take Critical Focus and start qualifying for the other critical feats, or at least confirm more often.
