Conversely, get rid of K:D. Anyway here's a few issues:
1) Over kill exists [ie, not all hits are important->Simply hitting somebody is not important]
2) Taking a blow [blocked or not] in place of an ally, allowing them a free hit, and he kills an enemy, that is pretty big assistance
3) Dehorsing somebody and having a team mate kill them when they're down is pretty big
4) Holding attacks to force a block is useful
5) Forcing a shielder to ping pong is also very useful
If you need a score to tell you how well you're doing, something's wrong.