It´s not realistic , but i think 100% Friendly damage to self and 0% damage to Friendly would be good, because archers would think twice about shooting in melee-fight , and swinging damage your mate would be less , cause they don´t learn from teamwounding.
Now it´s like this :
Archer shooting in melee .... hm .... nobody seen , that i hit my mate ..... no sry said .... just shoot , and shoot .... oh .... another teamhit .... but not a kill .... must say nothing .... shoot shoot shoot .... ups .... i headshoted my mate .... er .... better say nothing , maybe nobody had seen the direction, from where the shoot comes .... shoot , shoot .... ups ... teamhit .... hm .... shoot shoot ... teamhit ...
Round lost .... MAN ! My melee mates are so bad .... they loose all the time .... shit melees .... why don´t they take a bow ?
Or : Cav player in full speed , targetting an enemy .... he sees a mate comes by and get´s into melee ... but he hold attack and speed ... the enemy and mate turn sides .... ups .... teamkill .... hm .... ok .... i say sry .... next target ... ups .... bumped my mate , and he´s killed by enemy , cause he couldn´t defend .... hm .... say nothing .... next target ... and so on ...
If all this teamdamage would be reflected , it would be much more fun to play for the ones who are cautious with their hits.
One thing : Most of the archers are real good , cav also .... some archers and cav are fantastic , but the few who aren´t , but try , and try , and try are really annoying , and for those a teamdamage-reflect would be really good.