Def feint in L! Lucina?

Just pulled a +SPD -hp and I'm so hype! I have a S!Innes laying around and I'm wondering if def feint would work on her. I know a lot of people have been using that atk/spd link which sounds great too but I don't have Sumia. I'm just wondering if it'll be worth it over desperation or chill def. Your thought? Edit: Guys ignore this ignorance XD