The thing is she has low hp and gets hit hard. For that I don't use her. I use Roald cuz he has that healing increase buff which helps and has saved me a few times. Roald can also take twice as many hits as Felicity can.
well i give Veradux instinct and Roald vitality,i give them armor according to their highest stat,so i guess i'll give Felicity speed armor(i tried giving her other armor,but speed worked best since nobody could hit her very often).
She does the most damage of your team mates but she also has the least utility. Also her knife throw is bugged and actually increases the enemy's speed.
She is your best option if you need to kill stuff quick (city councils on easy, time bomb). Otherwise she is probably the worst option, although she *might* be more useful than roald immediately after you got her as she is level 22 (she can instantly equip royal armor and supremacy).
tl,dr: .. she is perfectly usable as she has the highest damage output but sticking with roald + dux is more foolproof most of the time.
(yeah, I know, old topic but hey, there are still people playing this game xD)