Wraithlord Exarch: help with points cost?

I was just wondering how people point out special characters. My buddies and I have been considering doing some sort of campaign, and a possible scenario and scenario reward occurred to me. The scenario is called "Wraith G(u)arden", and is located in what was once a 'factory' where bonesingers made the bodies for wraithguard, and the objectives are all clusters of fully constructed wraithguard bodies. Rather than take and hold objectives, non eldar players must destroy objectives (they'd have an armor value like vehicles or something,) whereas Eldar players have to get a psyker to objectives and then make some kind of roll to activate the wraithguard (who then join the Eldar army). Each objective, or activated unit of wraithguard, destroyed is one victory point, and each activated unit of wraithguard at the end is a victory point to Eldar players. Might have to be uneven points to be fair, but that's not really what I'm posting for advice on (though if you have any I'd like to hear it!).

The reward for victory I had in mind for Eldar Players was access to a special character: a Wraithlord Exarch (Dark Reaper) with a wraithsword, EML, BL, flamers, and the crack shot and fast shot powers (only one applicable to each weapon, each can only be used on one weapon a turn). The wraithlord exarch is an HQ choice, and if he is selected the eldar player can choose units of wraithguard as troops even if they are fewer than 10 models strong. My thought for cost was 165 for the base stats and weapons (while you technically can't have 2 weapons and a wraithsword, it doesn't strike me as too unbalancing), then a further 45 points for the exarch powers (150% of regular cost because they're kind of illegal) for 210 plus whatever the force allocation chart adjustment should cost. How much do you think that should be, and is this cost totally unreasonable?

For the record I don't play Eldar, I just thought that each faction should have a scenario where if they win they get a special reward for the duration of the campaign, kind of like DoW Dark Crusade.