Now I have been looking at the weapons of the Eldar and this one popped out to me as having some uses.
First it is in the hands of your Exarch who will hit stuff on a 2+.
Second it has three attacks and is Assault 3.
Third it is AP 2 in both the Basic rulebook and the Codex.
Fourth it can be used as a Power Weapon so no saves except invul's.
It only draw back is it strength which is only a 3.
But even with it being Strength 3 I do believe this weapon can be very useful if you are running into Terminators.
It is AP 2 and it gets three shots in the shooting phase and then in the Assault Phase your Exarch can use it for her 4 attacks.
That is 7 str 3 AP 2 attacks in one turn.
Which with some good rolls can kill off quite a few Terminators and would slaughter standard Space Marines since they would get no save.