You're right, I had to go back to Nesingwary and tell him off for not having a bow.  Then I took Fitz' throwing axe just to spite him.

For those without coordinates, there's a bluff that's visible on the map just northeast of Oshu'gun, south of the road.  Tusker is at the top of the bluff, not visible until you go part way up.  You may have to clear through a lot of bull elekks to get to her.