It happens a lot in cRPG - You're in battle, engaged in duel. Maybe only one enemy is engaged with you, or maybe 2 or 3. A friendly cav comes around and teambumps you, leaving you on the ground to be easily killed by the one(s) you were fighting. Rage ensues. Perhaps instead you get a friendly arrow in the back. Believe it or not, they are trying to help, and the path to victory is much easier to achieve with teamwork.
While some cav just can't be helped, you can at least help the competant cavalry bump your enemies for the kill. If you see a friendly cav moving in to attempt an assist bump, back away from your opponent. Hopefully, the ones you're fighting don't just facehug. This extra space will give the cav an easier bump. If you happen to be fighting one of the more aware ones, they might try to kill the friendly cav as they ride past. In this case, carefully give your enemy a nice slash in the back for their trouble, if you can.
In the case of an archer, sure, some might be a lost cause. However, if an archer is trying to help you, the best thing to do is to manuver so that they have a clear shot of your opponent's rear. While they might still miss your opponent and hit you, at least your opponent is a larger target.
In the end, archers and cav don't want to TK, they want a multiplier, and some like helping. Doing the above can help them help you.