Mightn't Careful 252 HP / 252 SDef possibly be better to even out its defenses, given that (especially with Eviolite) Doublade's Defense is already quite strong?
I was actually thinking a lot about that one, but i made some calculations and i got this:
160+ SpA Heatran Flamethrower vs. 252 HP / 252+ SpD Eviolite (custom): 234-276 (72.67 - 85.71%) -- guaranteed 2HKO
252 SpA Gengar Shadow Ball vs. 252 HP / 252+ SpD Eviolite (custom): 192-228 (59.62 - 70.8%) -- guaranteed 2HKO
252 SpA Life Orb Alakazam Shadow Ball vs. 252 HP / 252+ SpD Eviolite (custom): 172-203 (53.41 - 63.04%) -- guaranteed 2HKO
252 SpA Hydreigon Fire Blast vs. 252 HP / 252+ SpD Eviolite (custom): 186-220 (57.76 - 68.32%) -- guaranteed 2HKO
0 SpA Jellicent Shadow Ball vs. 252 HP / 252+ SpD Eviolite (custom): 110-132 (34.16 - 40.99%) -- guaranteed 3HKO
Which isn't actually impressive since it got 2HKO at best by almost every Super effective special attack... But in the physical side it can be as amazing as:
252+ Atk Landorus-T Earthquake vs. 252 HP / 252+ Def Eviolite (custom): 140-168 (43.47 - 52.17%) -- 10.94% chance to 2HKO
252+ Atk Life Orb Sheer Force Darmanitan Flare Blitz vs. 252 HP / 252+ Def Eviolite (custom): 276-328 (85.71 - 101.86%) -- 12.5% chance to OHKO
252+ Atk Thick Club Marowak Earthquake vs. 252 HP / 252+ Def Eviolite (custom): 186-222 (57.76 - 68.94%) -- guaranteed 2HKO
252 Atk Life Orb Mamoswine Earthquake vs. 252 HP / 252+ Def Eviolite (custom): 151-182 (46.89 - 56.52%) -- 83.98% chance to 2HKO
+1 252 Atk Salamence Earthquake vs. 252 HP / 252+ Def Eviolite (custom): 122-144 (37.88 - 44.72%) -- guaranteed 3HKO
252+ Atk Choice Band Tyranitar Crunch vs. 252 HP / 252+ Def Eviolite (custom): 158-188 (49.06 - 58.38%) -- 98.05% chance to 2HKO
If we compare the Viciousness of the attacks, the physical ones are able of bringing down even some resisting pokes because of it's sheer power... but even the most ridiculous one (Adamant + Life Orb + Sheer Power + STAB Darmanitan Flare Blitz) have a low chance of a OHKO... but at the same time, the Special one can fall also in two hits just because of a non STABed Shadow Ball from Alakazam which isn't that deadly to a lot of pokes...
So i think it's better to use it carefully to sponge physical attacks like a champ and try to deal as much damage as possible since even with no investment it can deal some good damage with SE moves, and Iron Head, Sacred Sword and Shadow Claw(Sneak) can hit SE 8 Types which isn't a lot but it's something... also you can run Swords Dance for a more offensive approach if you like it...
Of course, a Special Spread can help against resisted and neutral attacks, but they are even going to hurt, so... why bother about that when you have an absurdly high defensive stat?