Untill when was the pugio used?

[Salvianus]

I don't know of any off hand, but you may take the view that an absence in the finds does not necessarily indicate non-existance. Even if one form went severely out of 'fashion' I suspect that would just fuel a thriving second hand market until the things just fell to pieces.

Personally, I believe there must be a reasonable margin for error in any evidential record - & even for individual pieces: I always think of the 'Coppergate' helm which appears to have been around for many years before it's last outing.

Cheers