Still not sure what that hallmark's for. It's not the SK hallmark though. That's in Freeport. I don't have my book with me but the NPC/Zone you need is in the book under the "Hallmark Quests" section.
Basically, you go kill the Dervish Go-Between in the commonlands (south of the maze/FG) and then you must go fight more Dervish in a instanced zone called the "Storage Room" in the Serpent's Sewer:
http://www.gry-online.pl/eq2/maps.asp?ID=44
The instanced battle is quite easy. Getting there is harder. If you're trying to get there solo, I suggest just sprinting past all the aggro mobs. Most of them won't give chase for very far.
Once you're inside, you've got plenty of time to buff/med up because they won't be in aggro range. There's 2 sets of mobs which where green and blue to me at lvl 19 (solo rated with arrow down). Pull the green mobs first with Righteous Anger and med/buff and then pull the blues. Very simple fight, nothing to really worry about.
[edit]
damn I type slow :)
Edited, Tue Nov 30 13:50:45 2004 by subvert