User blog comment:IamJakuhoRaikoben/Chapter 501: Mari and Randi, Review./@comment-24499036-20160912204638/@comment-7418318-20160913140712

Just because she didn't use any others doesn't mean she didn't have any others.

The keys she used against Lucy worked so well there was really no reason to use others. Between the power cost of switching Spirits and the limited times Spirits can be summoned, there are even two very good reasons not to show any other Spirits off.

Also we never got to see Angel's keyring or whatever she uses to store her keys. We only saw the keys that she used exactly when she used them and not a moment sooner.

There's also the possibility that she just went and bought (or stole or found or was given) new Silver Keys during the last timeskip. Sure she has her new Angel Magic, but we know little to nothing about it's limitations, so we can't really judge whether some Silver Keys would be useful as backup or secondary magic for Sorano.