Comparing them to the weapons alongside I would estimate them to be 20+" long .
Two and a half inches penetration is all that is needed to deal a fatal wound ; they would also slow down approaching troops while they stopped to pull them out of their bodies .
A handfull of these thrown with force would have a shotgun like effect .
Easy to dodge one spear , not so easy to dodge several at once .
Most accounts of cotta battles refer to 'showers of spears' being thrown .
I do find it unusual not to have seen them in the flesh (N.P.I.
) before .