The ambush came too fast.
If Dakker had been a different Strider, one with better reflexes, maybe he'd have been able to flit out of the way of the blow and be fine.
Dakker is not a different Strider and he did his damn job, which is to get everyone out of harm's way, and if no one recognizes where the hell they are now at least it doesn't look war-touched, and it's a damn shame to blame someone who's bleeding to death for his own injury while you're trying to save them.
Especially if it doesn't work.
The death toll sounds while Aduva is still desperately trying to frost over the wound for lack of any cloth clean enough for bandages.