Maribel is more for those "bursts" where you know a lot of strong enemies will go through a certain path, and her AW passive is 15% to totally negate an enemy attack (per physical attack) that, and she has some nice HP making her a good lightning rod
I use her as my second HA (first is Bernice) and se has done a really nice work, i have her currently at AW60~ish and she reaches over 700 AT with skill up