I'll be honest, it's not the friendliest of names. And with no obvious nickname, it doesn't seem like the best choice. It would take a lot of getting used to, and it does look more like a medicine than a person.
If you really did want to give it a go:
Alexander Abraxas
Samuel Abraxas
James Abraxas
Miles Abraxas
Frederick Abraxas
Abraxas
John ( with 'AJ' as an option in case Abraxas is just too much for the kid)