When I grill swordfish steaks, I like to keep it pretty simple. I'll saute in a pan or cast iron skillet with a combination of white wine, lemon juice, olive oil and just a tiny bit of salt and small amount of chopped onion.
A few minutes on moderate heat and then transfer to direct heat on the grill to sear and finish.
I like this method. It's simple and easy, and you end up tasting swordfish rather than a bunch of sauce.
Swordfish doesn't hold all that well, so you need to sauce it or it'll dry out in a steam table pan. I make a mild beurre blanc and use that. If you're grilling to order salt, pepper & butter is hard to beat.
We do a lot of swordfish over here. Not for vending/catering, just eating. Slamdunkpro nailed it, this fish will not hold well. Your best bet is to buy the swordfish in filets and cut them yourself, thin... about the width of a AA battery.
Cook them over a hot grill (generously oiled) and you should be able to crank out 20-30 portions of swordfish in 4-5 minutes.