Why are Theurophoroi so weak?

[hoom]

[Keltohellinikoi have] got 9 armour and 11 skill, while thureophoroi have 11 armour and 9 skill.

That defense skill is the big thing.
For those who don't know why, I suggest playing around with Drapani a bit.
Basically no armour but high skill & very deadly weapons. But they take relatively few losses.
Zoom in as they butcher stuff & you see them doing lots of the dodge/defense animation as they use their defense skill to dodge hits from the other guys.

Theurophori are sweet. Not flashy but very good at defending the flanks of a phalanx or beating up weaker skirmisher types.
Sufficiently good that in a difficult battle, they can generally be trusted to hold off stronger units until a better unit is available to relieve them.