I did some searching and I didn't anything like this, so here it is.
As everyone knows (Mostly everyone), C4 is an abused and overpowered item. Even with its nerf, it is still way too strong! It is a game breaking item which needs to be gotten rid of. I mean, when 2 sneaks can defeat 5 or more fully geared soldiers with C4, you know there is a problem. Since there is no level cap and skill points are easy to gain, any PvP character can get 300% traps for some MASSIVE C4 damage. But enough of my ranting, I want to propose my solution.
I suggest not only to be rid of C4, but to replace it. A Proximity Mine would be the ideal solution.
The Claymore would have a set 80-120 explosive damage, which is NOT affected by the traps skill %. Also, maybe give a 20% chance of crippling each leg. It will detonate when the player comes in to a close proximity (Maybe 3-5 hexes?) from the front of the mine obviously. The Claymore is not seen by the player unless it is in his/her direct line of view. It could be deactivated by using the traps skill from behind. Claymores could only be found in lockers, same as Frag Mines.
Again, this is just my opinionated solution.