how often does the damaged helm drop? if i only have to kill him twice that's fine, but i don't wanna be KOS, so if you have to camp him for days i'll just wait till some uber high-lvl ogre/troll/iksar runs through and wastes a buncha guards...
There is one spot where he can be taken one on one IF you kill REAL fast. Turn right from the West freeport zone, and go down a little ally on the right, here, under the lamp post, he stops. Check outside near the mass of guards for another high level gurd that is sometimes near the end of the ally. If hes not there, kill, but if he gets away, you get 6 guards on you which, as you can guess = death. Hope this helps.
He is a roaming guard, patroles from the gate to the wfp zone to the docks and back to the gate, he is around other guards all the time, good luck getting him in a 1-on-1, Most of the time that I see him is in the area from the gat to the area by the PoD.