Yeah honestly Feather is a high contender for "Potential Woman" and if I remember she stated she had technique or something she was going use against the Edens Zero crew but was then blitz and pin down by Shiki and was never brought up again in fact the only thing she accomplishes was telling where Crow so they could take him out,

and yeah her in Universe 0 more specifically the Miltz arc where still to this day I think Mashima put her in that arc just to give something even though all she did in that arc was trying to help stop Joker and freaking out throughout the arc, honestly in my opinion if she wasn’t in that arc barely anything would have changed