AOO and Free actions.

[Aestolia]

Which brings up the original question: Could the monk drop the crossbow as a free action to do the grapple?

I'm still going to say no on this one, we've already determined that you can only perform free actions when taking other actions "Normally". AoO's aren't part of a characters 'normal' actions in combat. (see PHB. 141)

Exceptions to the rule are usually written right in, like speaking ("...even when it isn't your turn...")

 

[nittanytbone]

Could the crossbowman have been wearing spiked gauntlets -- and thus threatened -- to get the AoO? At the end of each round they remove a hand from their Xbow as a free action, then at the start of the next round the replace their hand as a free action.

Also, could they have used the Xbows as improvised weapons at -4 to hit in order to threaten nearby squares?

I imagine that running past someone holding a bar stool as a weapon in a tavern fight would provoke; why not someone holding a heavy crossbow?

 

[Hypersmurf]

The monk either needs to be able to grapple with his feet (something I find dubious unless he's an ape... hey, stranger things have happened)

Jet Li Visual Reference

The scissors-shaped takedown at around 2:29 is one way I envisage a monk initiating a grapple without using his hands.

Also see Yuen Biao:

See 0:09, 0:55, or - my personal favourite - 4:04. There's another potential at 5:36, I suppose.

-Hyp.

 

[azhrei_fje]

I imagine that running past someone holding a bar stool as a weapon in a tavern fight would provoke; why not someone holding a heavy crossbow?

Yes, this seems pretty obvious to me. Granted, they would need to use the "improvised weapon" rule and take the -4 penalty to attack, and they would be using the crossbow as a bludgeoning weapon...

Could they pull the bolt out of the crossbow and stab with it? I don't know...

The problem with ruling this way is that the number of AoO's proliferate ridiculously! And I'm not sure that's good for the story/game, so I'd stick with the original "crossbows don't threaten".

I'm surprised that one of the guards didn't have a tripping weapon: spiked chain, bolas, or a really long leg. (Hmm. Suppose a guard was swinging a set of bolas around his head, could he simply let go and hence attack with the bolas?)

 

[Dross]

Could the crossbowman have been wearing spiked gauntlets -- and thus threatened -- to get the AoO? At the end of each round they remove a hand from their Xbow as a free action, then at the start of the next round the replace their hand as a free action.

Also, could they have used the Xbows as improvised weapons at -4 to hit in order to threaten nearby squares?

I imagine that running past someone holding a bar stool as a weapon in a tavern fight would provoke; why not someone holding a heavy crossbow?

Spiked gauntlets, maybe, but the attck would need to be with a spiked gauntet which may not allow grapples via RAW.

Having a Xbow ready to fire IMHO isn't having a Xbow ready to use as a club similar to hold v weild a weapon (you need to weilding the weapon appropriately for the intended use).

But as someone said, possible rule 0 or bad terminology on the DM's part.