Best weapon against Lorica Segmentata?

[Sean Manning]

Dan, it doesn't matter to me if the weapon is from the era in which the segmentata was in use or not, all I want to know is what type of non-gunpowder weapon would most effectively damage a lorica segmentata

Could you tell us why you are asking this? If its to chose what outfit a neighboring culture uses for war, pretty much anything used by a culture which often faced metal armour will do; if its what a character picks to fight one of these soldiers, the best choice for them might have more to do with their training and available weapons than some theoretical measure of effectiveness.