The equipment just give them good equipment before make them vassals so they don't change (in your case a templar knight full set), as for the map icon the one you need to replace is this: player_horseman 0 ikon_tevton_knight 0.150000 112 0.150000 0.173000 0.000000 0
the "ikon_tevton_knight", although once they become vassals of your faction after a while the icon shall update to the templar icon. As for the banner is more complicated.