Absolutely nothing. The spell doesn't prevent him from approaching you, but should he lash out... no damage he attempts to inflict on you will actually take. His blows will glance off, his blades will not pierce your skin- absolutely nothing he can do to you in this world will cause you harm.

[It's a fairy straightforward spell- one of the few he possesses, but considering the last person he gave it to was Snow White and she has his number... yeah.]