Just that the fact that they might be enslaving two sapient races, particularly two they can't actually communicate with likely wouldn't phase them much.

A fireball is maintained by a weave. While lightning is simply made and directed.

The fact that balefire disperses after passing the edge would mean that it needs the weave to continue, much as fire would. But... Rather little the OP does is of the OP. The closest it really gets to that is direct effects of the weave. Not the fire itself, but the initial ignition.

So really, the real question is whether or not the balefire is simply the effect of the weave, or a thing made and maintained by the weave.

I'd lean towards it being a thing, but not sure the text is evidence enough.

Going back to fireballs and lightning... Being untouchable to weaves isn't THAT good a thing to be. Useful as a surprise to have up you sleeve, but it only really protects you from weave like fireballs or flows of air which involve the weave actually touching the target, and even then... Wouldn't be all that hard for a channeler to simply cook the thing in the center of flows of fire, they simply have to avoid touching it with the threads, or just use Deathgates. Unless it touched it on the outside of the gate, the loss of weave would just cause the gateway to close. Or just use lightning. Lots of lightning. One of the favored battle weaves of channelers, and it's immunity to the OP wouldn't mean anything, just ask Mat. Hell, just take a page out of BS's book and forget the hardened air in favor of just plain old wind. Throw the thing around like a rag doll with no need for the weaves to actually touch it.

Don't get me wrong, the things do work as assassins. It's just that they were painted as these nigh unkillable beast, that even the Forsaken had big issues with handling... When we have SEEN that the Forsaken do know how to counter people with ter'angreal that do much the same thing.