If you have lv.251+ off-hand like Scourgelord's Baton or even Relentless Gladiator's Compendium I think you should go with Wrathful haste dagger + off-hand because of the scale factor of Int which you will get atleast 80+ int from those off-hand are better than the haste you lost from Dying Light and you also can reforge another stat from you off-hand to haste or hit(if there's no haste on it).
Just saw you've aslo linked the off-hand in the first post. Well in this case the pvp dagger+off-hand is better.
78 Int is > 24 Mastery + 27 haste even tho haste might be the highest value stat for destro. So trading 27 haste+24 mastery for 78int is indeed worth it.