Vigilator comes to mind.
Indeed, but then the vigilator is wasted. His rifle loadout means he is a shooty character meant to hang in the backlines with recon or seekers, and not only will he be taking away one HQ from your FOC, but also Warrior's Mettle from the poor slayers.
The other idea I had was fishing for the Master of Ambush starategic trait from the BRB... until I remembered that the wolves are locked with their own warlord table that is.
Creating cool synergies that play to the legion's strengths is harder than it seems, between the compulsory slayer troops, the HQ tax of characters that cannot join said troops without debuffing them, and the limited access to warlord traits, the listbuilding of the VIth is surprisingly deceptive.
The fluff hints at a flexible and loosely organized force with a diffuse command structure, whereas the crunch is very restrictive.