I honestly would like to see Doublade in B/B+ or even A-. It walls a good range of strong mons at the moment, including Crobat, some M-Aero, Jirachi (got to watch out for Fire Punch burns but Fire Punch itself hardly scrathes Doublade), and the rising Cobalion and Virizon.
It beats SD Luc and NP variants without Dark Pulse (even +2 Crunch won't OHKO +2 252+ Atk Life Orb Lucario Crunch vs. 240 HP / 0 Def Eviolite Doublade: 208-247 (65.2 - 77.4%) -- guaranteed 2HKO) whilst Sacred Sword and Shadow Sneak will kill it everytime
252+ Atk Doublade Sacred Sword vs. 0 HP / 4 Def Lucario: 256-302 (91.1 - 107.4%) -- 43.8% chance to OHKO
It can switch in to Blissey with little fear whatsoever unless they are running Fire Blast for some reason, and can proceed to setup. Does the same with Fairies such as Florges and Aromatisse and Curselax, all of which are abused.
At +2 Chande cannot reliably revenge it and it can deal quite a lot of damage to unprepared teams.
It's bulk is great and can take even super-effective hits quite well.
This thing also pairs incredibly well with Blissey which has no troubles receiving wishes from.
Anyway, I've had a lot of success with it and think it should be at least higher than C.
(And I'll rant about Gastrodon later)
I did a Doublade nomination a few pages back but Pleasure Kitten shot me down :[