Also I thinkt aht archers should be penalized extra for hitting team mates, and get a few more points for hitting enemies. Hitting enemies with arrows is extremely useful and since they wont get proximity bonus they need some sort of incentive. Also hitting allies most times is a result of simple greed and bad choices.
You would be amazed at how many tw/tk by archers/xbows are due to the actions of the person that gets tw/tk;
1. walking in front of a drawn bow/aimed xbow
2. arrows are so slow you shoot and your teammate actually runs into the path of your arrow
3. your aiming and a teammate runs from the side of a building into your arrow's/bolt's path
4. you get 2 arrows in a guy and then your teammate runs up to get the killshot just as you release your arrow
there are so may things that happen during the "fog of war" that the archer can't control. I had a guy get really mad because I teamwounded him. I was across the town and had shot a xbower (who was on a wall) twice. I aimed the arrow at his head and released once more. Just as I did a teammate jumped down from a higher wall and killed the player right as my arrow reached its target (and instead hit the teammate in the back.) I was penalized for the hit (reported) but how could I predict the actions of the other guy. My path was clear to shoot when I released.
You are not going to get a perfect system, unless you just do away with scores altogether and let people play. Scores do take some fun out, but they also keep us playing in a well regulated way; rather than just a free-for-all.