I rolled up a 14/1 bf paladin/monk to do some testing. Feats were twf x3, pa, cleave, great cleave, imp crit blunt. Here are some results.
Holy sword with nothing equipped seems to do nothing. With wraps equipped, it seems to give +2 enhancement bonus, +1[w], but no crit threat increase. I didn't test if it increases crit multiplier, but the inventory sheet doesn't show it, while it does show an increased crit range/multiplier for kamas.
Great cleave continues to offer an off-hand proc chance with unarmed, but not with regular cleave or kamas. Both kotc cleaves give off-hand procs unarmed, but not with kamas. This means that you can actually accumulate vulnerable charges on enemies with nothing but avenging cleave unarmed (3 sec duration, 5 sec cooldown). Kotc cleaves with no weapons or wraps equipped performs an animation and the attack/hit sound, but does no actual damage.
Exalted smite has the full 6 second cooldown, but it should have a 5/4/3 sec cooldown. It has a pretty cool looking backflip animation unarmed, but it interrupts your attack chain. I didn't check if it actually affects your crit range/multiplier.
Holy retribution has a cool looking jump/flip animation unarmed, but it takes about 1-2 seconds to perform, and then you pause for another second or so before you can continue attacking. This took a bit less time using kamas (about 3 sec from start of animation to next attack unarmed, 2 sec with kamas). Unlike with melee adrenalines, you can't interrupt the pause with another active attack like cleave. It does regenerate smites, but at the end of that pause (whether or not you actually hit something). Also, it can't be used in public areas. Tavern brawl areas work though.
Base large/tower shields purchased from the harbor vendor gave 10/15 prr and mrr, even though they have no enhancements on them, and I wasn't proficient with tower shields.
Edit: more bugs/tests
Light/medium/heavy armor gives 15/30/45 prr/mrr with or without enhancements or proficiency. The prr based on armor type and base attack bonus still requires proficiency.
Song of arcane might is still bugged.