Do we even have a wound? It sounded like it just lodged in our armor.
Also, I don't think we need to scramble to counter that idea of cowardice. That only reinforces the idea, in some ways. It's filling the cracks with water. It makes us look insecure, indecisive. No, we need to build on what we've done. We did it for a specific reason. We can prove our valor against any man in the ranks. But to meet an ambush and rush headlong into the enemy, without knowledge of numbers or their own preparation, when they've already proven themselves this wily?
We did not flee. We conducted an orderly retreat. We have no need to charge into traps. We will kill them and burn their village, and our deed will be forgotten. Once we get back, begin immediate preparations to set out again. Don't give them time to set further traps, but don't act like we're in a hurry. Order, discipline, and a fierce inevitability. That is what we need to project. We are warriors, not savages. There is no act to put on. We may have made a mistake. Let's own up to it, if we need to. Any man that calls us a coward will be treated fairly, and then told that he may choose the battlefield of his choosing, where we will fight him ourselves.
Twisting back on ourselves because we got a poor outcome is essentially the worst thing we can do.
Remember: We are only suspected. They don't actually think us a coward yet. This is the caution zone, not the 'ohshit' zone. We need to make sure we take action, but we don't need to do so in a flurry, or we will be a coward, one who fears for his honor.
Our honor is in no danger. We will take our Thralls from them, after all. But by all means, if you would like to contradict the gods, who have essentially told us that we would die, and our colony would be abandoned to the whims of these people, then you may do so yourselves. We will whet our blades and ready our bows for the raids to come. Tonight? Probably not. Tomorrow night? Probably.