If you're already at 50 I'd just push to at least clemency. Stoneskin is nice in that it can save a bad party for a wipe, but a party that knows what its' doing won't ever need you to cast it. I usually take it first just so I don't feel so at the mercy of my healer being decent. That being said, Clemency mostly replaces the uses you'd have for Stoneskin, and since its' such a meaty and quick heal you can get yourself or someone else back in the game really quickly so you aren't biting into your DPS too badly. You can usually get two casts off before you run dry of mana, and then an Ether or a couple of Glory Slash combos will get you in a third. It can also pair with Convalescence and Divine Veil which can take you from almost dead to back to full health, which is kind of how I'd recommend you start using those abilities.

Bloodbath is actually a pretty potent amount of damage mitigation, and I'd recommend getting at some point. Pair it with Fight or Flight (or is it Flight or Fight?) and just pop it when its' ready to help take some burden off your healer.

Mercy Stroke is nice to increase your DPS. It's not going to suddenly sky-rocket you to the top of the charts or anything like that, but its' nice to have if you really care about your performance. It -can- have some actual utility in boss fights: Pull an add, burn it down, and finish it off with Mercy Stroke to get a nice juicy heal. Sometimes difficult to pull off if your DPS is on point but then... you probably don't need the extra healing if your DPS is actually trying.

Fracture stops mattering as soon as you get Glory Slash, and is a very tiny DPS increase otherwise. Foresight technically increases mitigation, but by such a small degree that its' almost negligible. Protect is nice if you're soloing or to troll your healer every 30m by casting it before they do. You can't use Raise in battle so its' practical use is extremely limited; It's usually faster to just let the guy walk back rather than hope the PLD has it sloted.

I'd suggest at least Bloodbath and Mercy Stroke, although neither is strictly necessary. You're mostly out of the content where stoneskin would have been useful.