User blog comment:B214/Chapter 501: Mari and Randi/@comment-24546844-20160912135626/@comment-7418318-20160912142646

Yeah, but Erza can't change armours once time is stopped.

So unless Dimaria is stupidly trying to play with Erza or Erza approaches Dimaria with the armour already put on, she'll never get the chance to use it.