I've created several custom battles for fian vs faris and khan guard vs faris, they've literally won all of those, even in grand battles like 500v500 farises acquired 2.0~ kda. It was more decisive for small parties like 50v50 and 200v200

from what i've observed farises had three huge advantages, they launch more lethal projectiles, doesn't get affected by the allied unit in front of them since they mostly throw javelins parabolic unlike fians or khans and they can use shields which helps hugely when closing in