I'm just going to go through some of the normal check lists, so don't take this as being a jab at your intelligence or anything along those lines.
1) Are you talking to the proper NPC to flag the quest? It's Oggbi in Port Bastok.
2) Is it a natural 250 skill? I'm fairly certain that skill through merits don't count.
3) Are you absolutely certain you don't have any other weaponskill quests active at the moment?
4) Are you going on Monk or Puppetmaster to talk to the NPC?
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Lady Jinte wrote:
Vlorsutes' Negotiation Skill rises 0.2 points
Vlorsutes' Observant Parent Skill rises 0.3 points
Vlorsutes' Argument Diffusing Skill rises 0.1 points