I think there are only 3 areas to gain the Ebon Vanguard Title.
I've been running from Doomlore Shrine and clearing all of the Charr along the left side until I get to Sacnoth Valley.
Once in Sacnoth, I keep the Charr that are on the right till last. I does seem to take a lot longer than the Norn.
It's because there are less enemies to kill, whereas outside Olafstead there are over 300 enemies.
The best thing to do is hunt outside Doomlore. I clear some of the Mantis-things in the woods, then go down the left side and around from there. It all depends when you get the bonuses - sometimes you won't get more than 2000 faction a run, other times nearly 3000.
Doomlore, go south towards the open field, AVOID rocktail, but hijack the siege devourer, Grant Theft Devourer style, then cruise around the map in the siege devourer with the hench/hero and bomb your way to high scores.
i got to shadow agent in half a day, by just going out of doomlore shrine getting on the siege devourer in the field to the south then head into the sauking valley or whatever its called, when there go down the easy and south first clear it down there, then i move north and clear out the charr stronghold last as thats when you want to have the +4 rep bonus and hopefully get the boss bonus as there are 4 bosses in the area. usauly get 4k per run.