Perhaps the plumbata filled that niche?
They were among the aux I’d guess (without typing in a search, I’m tired, and just got the old CPAP cleaned up so I can nap decently in the recliner in an hour or so).
Oh, okay, here, some legionaries carried them later in the main imperial period, by that time the only thing Roman about the Roman legions was the training and Latin:
http://en.wikipedia.org/wiki/Plumbata