best thing is just to lancet the dudes over and over till you're sure they don't have any lancet skills anymore.
after each succesfull lancet (that means if you gain a lancet skill) your od fills up then just use it, use white wind (if you have it) to cure if nececarry and else just an offensive magic.
after you got them all, you can do this to make the battle easier. look up the internet or somewhere (I can't be arsed to look right now sorry) for the amount HP they have and then try not to kill one of them till both have really low HP, cuz if you kill one of them the other uses berserk or haste I thought... so u won't go trough that hell then.
And you should be able to beat this fight at all times since the strength of Kimahri is spose to b about the same as they have.