(trolling a bit): what about levies and kleucheroi? I presume It'd be much more profitable to main tain them as farmers as their loyalities are not as close as that of higher ranks.(note this is a question)
concerning the ransom mechanism, ransoming mercs(and not the odd pezhetairos, princeps, Dugunth(damn singular), Steppe rider etc.) would not really make sence tho.