User blog comment:Wrath022/Chapter 516: The Truth About Enchantment, Review/@comment-24546844-20161227201713/@comment-7418318-20161227220201

I doubt that Wendy could do it that easily even if she knew how to cast that spell.

Sure Wendy managed to counter Irene, but I'm pretty sure that this was only due to Irene getting caught off-guard, rather than Wendy being anywhere near equal in terms of ability and power.

Though it is rather strange that extracting Fairy Heart from Mavis, while the First Master had no will of her own due to Invel's magic seems so much harder than taking Wendy's body, while Wendy is fully conscious, in possession of all her abilities and full will and most likely doing everything she can to resist.