They're a neat alternative sort of "heavy skirmisher" to peltastai. Better against cavalry, due to the spears.
Indeed. I'm planning to splash out on a range of mercs when things have stabilised with my economy; some merc hoplites, some Jewish spearmen (as thureophoroi-a-likes) and some Parthian horse-archers if I can find them. The rest I'll fill out with my regionals (Arabian light infantry and cavalry, Arabian slingers, Syrian archers).
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