I'm now sure how I missed the part about Scout Training, but now that I think about it, it's a really good fit for what I envision the chapter is good at. So here is my revised plan:
[X] Plan: Warrior of the Mind V3
-[X]Name: The Silver Owls
--[X]Colors: Cyan and Silver
--[X]Symbol: A White Owl clutching a key upon a Cyan field.
--[X]Creed: The Eyes of Justice are Ever Vigilant
--[X]Warcry: Fiat Justitia! (Let Justice Be Done!)
-[X] Scout Training: The Chapter's Marines are given more advanced training in the art of scouting, and as a result more of its Marines remain as dedicated scouts - even after being promoted from the rank of Scout Marine proper. They afford greater reconnaissance and intelligence gathering abilities, as well as improved capacity for stealth warfare.
-[X] Politics: This Chapter has grown adept at manipulating the surrounding political landscape. A sad necessity, in the increasingly politically driven Imperium.
-[X] Chaplains: The Chapter is blessed with more Chaplains than average among its numbers, and higher quality as well. Treachery and corruption will find it far harder to grow within their ranks.
-[X] Extra Thunderhawks: The Chapter has access to additional Thunderhawks, of both Gunship, Transporter and Annihilator models, giving them superior heavy air power.