Ayyyyyy look at that

Definitely. Lucina is still workable with even a Atk bane because of Thogn and Swift Sparrow. She'll still reach up to 53 Atk against melee units. Her boon is amazing as well, since she can reach up to 49 Speed with previously stated skills. She shouldn't have a problem doubling units.
You might also want to give her Moonbow to deal more damage to tankier units.

I got one today also, it's my second one so far, my last was lowered speed raised Res, and I merged in favor of this, and I have to say I regret nothing, the speed more than makes up for the loss in Atk your going to be double hitting everything and now, still surviving almost everything except big nuker mages and heavier greens, and even then they won't be double hitting you besides from skills.