How would they fix PLD 4.0?

[Reynhart]

Reduce potency of CoS (either dot or potency, not both)
slightly increase it's CD time (no more than 40%)
give it a chance to refresh on successfully blocking (around the same amount as low blow does).
This would allow a pld to do somewhat acceptable damage in an aoe situation, while still preventing it from being unfavorably underwhelming.

Considering the refresh is tied to blocking, it will do nothing for AoE situation when you are not the MT. Building on that, a very easy and less convoluted solution would be to make Shield Swipe a conal AoE on GCD. (With adjusted potency and TP cost)

Chivalry could be interesting, but I'd say it could swap your MP and TP (percentage-wise), to cover situation where you need a boost of MP.

[LilLemay]

Chivalry could be interesting, but I'd say it could swap your MP and TP (percentage-wise), to cover situation where you need a boost of MP.

*spams clemency, uses chivalry, spams more clemency* infinittte clemencyyy

[Reynhart]

*spams clemency, uses chivalry, spams more clemency* wait for the cooldown on Chivalry

Fixed that for you