I personally think the Rebar/Reblath outfit on Lahn is the best looking outfit. However, the only way you have access to the skin is if you take off all your gear haha. Would it be possible if you can add this outfit to the pearlshop>?
I think they should just give the tailoring coupon the ability to convert any armor in the game into a costume. Removing the stats and adding the classic XP, Vision, etc. stats. That way you could convert your Reblanth into a costume and wear it.
I do wonder why they chose to make the best armors the absolute worst looking in the game (Pearl shop???) but there should be a way to make any standard outfit into a "costume" to cover up my Cookie Monster feety pajamas...
It is plain. To be honest there are other armors she has that look much better; however, there is no disputing the fact that she has the best looking base-armors out of any other class. Valkyrie's armors I know for sure are ugly versions of school-girl clothes.