the Cardinal and I have had a good chat about this, and I think it was entirely possible, also a few good references
Justinian Mosaic has painted ones…
In Dura they found something similar to a spear shaft, which was painted wit red and blue bands, separated by a black stripe.
Spear-shafts in Danish bog finds were painted. Although much weapons from these bogs have been associated with the Romans, we can't be absolutely sure that they actually were Roman though.
Notitia Dignitatum, c. 394 AD. The coloring is medieval, but the tell-tale bands on the hastae longa are clear enough
[url:wvmducyb]faculty.maxwell.syr.edu/gaddis/HST354/Mar18/fabricae.jpg
