Quick Riposte is a great skill on many units, it let's you kill on the bait, part of the reason why Hector is so good.. with skill inheritance there are so many possibilities, I also like Desperation on her, it works well with Defiant Speed.
TBH, Defiant Speed is the first thing I would chuck on Lucina.
I agree, which is why I said this too. This is only a consideration when you're defending, though, and like I said I expect that Drag Back is a similarly huge pain to deal with.
Now, something that Vantage lets you do on offense is pull off a fighting retreat. You can let them initiate on you and then back away so that they charge into you again. I was expecting this to be more useful than it has turned out to be with Anna; I just don't find it an appealing option most of the time, and anyway you get some of the same effect with Drag Back.
I think being offensive would better tbh, just for board space. I find drag back to fuck with my positioning too much.