Ridoharjoz. They die quickly and kill very little, even when chasing routers. I used them extensively as the Casse, but that was only because I couldn't get any other cavalry. Sotoaras are also pretty useless when you've got access to Iasatae.

I rather liked Galatian Kluddolon back in the 0.80 build. They weren't much good at prolonged melee, but that isn't the job for light infantry. I used them for flanking and proving melee support to skirmishers.