Slice off its hand!
+1Hemomancy is unreliable. We're not strong enough to break a grapple. But our dagger... that we can depend on.
I did some extensive testing in arena mode. My test kobold just didn't have the size to break a trog chokehold, Competent Wrestler or no... but with
High Master in all things knife-related, he could reliably send a trog hand flying, even with an iron dagger. And this dagger's steel.
The test kobold would just about always land a hit with the weapon; he did, however, occasionally fail to swing with enough force to sever the hand. And he *had* to sever the hand completely; merely cutting a motor or sensory nerve didn't break the grapple. To counteract the kobold's lack of arm strength, I started using Heavy attacks. The Heavy attack is just as quick in the draw as a Quick attack and delivers much more force-- swinging like that, my test kobold was able to land a severing blow just about every time.
Finally, severing the limb causes the unfortunate amputee to reel in shock, giving us a moment to escape the cumbersome weapon rack.
So.
Slash at that hand as hard as you possibly can. Having released yourself, !!DODGEROLL!! backwards out of the weapon rack. Stay close to our allies. When a trog gets too close to the group, swiftly cripple it with Quick leg shots; dodge away and let a buddy kill it if a buddy's at hand, kill it quick if not. Don't get overwhelmed, always leave space to move about, and avoid becoming Tired at all costs-- a tired kobold is a dead kobold.
And try not to let the goblin die.