This npc is for adventure stone boosting after you do 20 adventure in MM.
For bag quest you need to hail npc at EF adventure camp and he will give you a note ... its very easy quest will take weight reduction to 50% and add 2 more slots to it.
Pardon my apparent ignorance, but what bag quest? Someone mentioned it being about a bag we got with LDON, I don't recall that bag. No one ever tells me anything anymore :)
It sounds like you're thinking of the Reinforced Satchel of Abu-Kar quest, available to people who preordered the CD-ROM version of the Lost Dungeons of Norrath expansion. Henai Silentwalker is not involved with said quest.
After you do enough of the Mistmoore theme missions out of Butcherblock, Vual Stoutest will tell you to find Hanai Silentwalker for more information about the vampires inside the MM theme. The more information you gather, the more power your adventurer's stone is supposed to have; I'm not sure if the information is worth anyhting else besides "mood".
He's at neg 1660 , neg 1240 past Llara on a higher plateau. Just zone in, turn right and keep going until you're at about the location and head for the highest ground you see.