Wings is more of a supplementary defence, and as such should be buffed AFTER addressing the core mechanics of DKs. DKs are meant to be able to take more damage than all other classes while applying constant pressure (hence no execute).
Some mechanics that need to be changed first:
-being a "tanky" class w/o relying on cheese mechanics (shield ulti+permablock)
-balanced resource management (remove permablock mdk without gutting stam)
etc. etc.
If you don't balance the core mechanics of the class within the current meta, than any changes to wings, a supplementary utility skill, will be superfluous at best resulting in another nerf that will throw the class further out of balance.
So a quick example (not a thought out one)
-greatly reduce block reduction glyphs and slightly buff sturdy and buff DK block through something like allowing minor stamina regen while blocking and reverting Helping Hands and Battle Roar back to percentage based values.
this would help all classes block a skill here and there better while diminishing permablock dps builds combat survivability outside of blocking due to less impen. Think of it like Magicka sorc shields. Strong with a shield up but 1 shot when they go down. So pure block builds won't suffer as much as they would be holding block forever anyways. This applies to PvE tanks as well. The difference is these PvP tanks will need to invest in base mitigation in order to survive while CC'd meaning they can't spec into damage.
The Battle Roar changes would help both mag and stam sustain their primary resource better w/o enabling mDK to permablock w/o investing into base stam pools.
With this change, you could reduce the cost of wings slightly and let it grant something like minor expedition after reflecting 1 projectile and granting major expedition plus snare immunity after blocking 4 projectiles.