What sort of venue is he performing at? How much time does he have? Glass eating can be faked, there's a version in 'Geek Magic with Tomas Medina.' Fire eating is pretty easy to learn. Can he juggle? If so he could juggle some breakaway bottles, smash them over his head and eat some of the shards.
It's a controversial one but a smash and stab / cups and balls type effect could work. He can avoid moral / legal problems by
not using the spectators hand. The problem with those trick swords (if they're the same as the ones I got)
Is that they don't look at all real, break really easily and can at certain points randomly curl up, revealing the method. If he does get 'Geek magic' DVD it also includes balloon swallowing, which for some reason spectators find more believable. I remember watching 'The b***** son of Tommy Cooper' (later 'The Wasp Boy' in the circus of horrors) perform genuine sword swallowing and he spent most of his time proving that the blades were real. Whereas I never have to prove that balloon swallowing isn't a trick because people don't see how it can be.
Invoke not reason. In the end it is too small a deity.