Auxilia, celtic knife?

[Titvs Statilivs Castvs]

Would it be correct for a galloroman auxilia soldier, Flavian era, to carry a kind of celtic knife/dagger/... instead of a pugio? I really don't know and I come to seek information by those who might know more about this.
If yes, could anyone give me some information about this; such as where I can find info on this, on celtic weapons and also, where I might buy such weapon?

Thanks in advance.