As a recent convert to WW I have to agree. I was very surprised it was NOT a single use item considering it's awesome destructive power and the way the furies helpfully target the largest ship in an armada!
Making it single use would be the simplest option imho.
Good point.
Maybe the furies' power should be lowered a bit. And the damage should be distributed to the whole enemy fleet (each ship should get weighted damage maybe).
Or maybe the furies' power could be divided by 2 at each use, until they become feeble and useless.
Or... each use increases the chance that the furies turn against their current owner. lol.
There is at least a rumor that you don't get any points for enemies blown up by the Furies. I haven't tested it myself, but since reading that I've used the gong a lot less.