Use mustadio to don't act/dont use them or put them to sleep or slow them or something. Once they are disabled like that they instantly become easier to target with all skills and abilities. Steal their shields first then their weapons. Also having someone with item skill it a good idea. I don't know man i found it easy if you do that stuff... you can also break their speed and attack or something.. oh concentrate helps on the thieving character.. if ramza has thieve skills and he can do that yell thing i think it would help alot probably
oh lower their brave that also makes it easier to steal.