@Cohors_Evocata, thank you for bringing up their answers. I agree with Trarco and Arjos that the spear depicted is ovearm, and doesn't show clearly if it's a javelin or something else. I defer to their expertise on the matter.
Maybe i wasn't very clear and the thread title caused some confusion, but i was actually refering to the neck armor that is depicted on the horse. I remember the EBI unit with full mail barding, and if i am not mistaken, this vase or one very similar was used as source.
The unit in question was the iberi lanceari
http://europabarbarorum.heimstatt.ne...y&category=any