my two cents.

Halone combo is the only current 3 ability combo that a PLD has. Riot Blade needs a 3rd WS to complete a 3 ability cycle, so I would say make shield swipe a finisher for Riot blade, but you would only be able to do it post proc, and that proc has to come during a riot blade cycle.

here is my proposal:

there are already 3 shield abilities. Start the fight off with shield lob... run in and stun, and shield swipe for +Damage, +threat.
If you proc a block in this 3 hit combo, shield swipe does AoE and Pacification. OP? maybe... Awesome? Definitly.