...Ok? So, what happens if the ship fires its kinetic guns while in FTL? By "FTL-combat" I meant something like this:
Ship is somewhere far away (beyond the light-cone of the targets). Ship gets targeting info using drones in the area of the target (drones are equipped with QE communicators). Ship enters FTL and moves in the direction of the targets. As it moves by them (moving faster than its light trail and, thus, completely invisible to any non-FTL sensor), it fires its guns (or drops bombs, or fires lasers if the boundary refraction problem can be overcome) without dropping out of FTL. No temporal paradoxes (apparently) induced because of eezo-born space magic.
You cannot do that either. If an object that is travelling in a mass effect field above the speed of light leaves the mass effect field then it instantly reverts back to sublight speed, releasing radiation plumes.