If the greeter has been killed using stealth, meaning the White Glove Society is not hostile toward you, there will be no one to confiscate your weapons for a time. Simply exit the casino, and your weapons will be returned to you like normal. Re-entering the casino, there will be no greeter and you will keep all of your weapons.
The greeter, if killed with stealth, will respawn in 3 days. However, if he has been looted, he will sometimes appear with only underclothing, mask-less, and with no weapon.