His ability affects all ships that fire at a ship in arch even the fireing ship is coming in from a different direction?

Correct.

So if i understand this correctly if i can keep a target at range 1-3 and in Etahns arch every one that has a shot on said target gets to change a voom to a kaboom

Yes. The shooter's position in relation to Etahn is irrelevant; the only thing that matters is whether Etahn has the target in arc at range 1-3.

That includes himself as well. Throw R2 and FCS on him and he's quite nasty. Team him up with Ten Numb...and you have my next tournament build. Goto "The Numb" thread for more information. Coran is probably more competitive but the crit machine is a lot of fun.

Also check the "Ten + Etahn plus ?" Thread. Both in squad list forum.