User blog comment:B214/Chapter 496: Forward/@comment-7418318-20160801113150/@comment-4933386-20160801120936

I think the Historia Spriggan isnt at full capacity is because they are very strong characters, in addition to the fact that Neinhart already summoned a lot of people and got defeated by Erza.

All of the Historia will probably be eliminated in which allows Neinhart to no longer need to use magic to maintain those and can fight Yukino (possible Angel too) at a greater strength.