I've known a couple of folks who within a very short time were able to do things along the line of apply a quick nikkyo to deal with an unwanted wrist grab. So, yeah, define practical usage...
Exactly what Janet said. I would go further and assume it's a translation error. Mastery is defined (in this context) by having nothing else to learn. It's the pinnacle and you can go no farther. I doubt you will find any Aikido practitioners who are willing to say that they are finished learning Aikido and they know everything there is to know about it, regardless of how easily they are able to send attackers flying in different directions.
I can point out quite a few people I know personally that can and have handled themselves with ease in actual combat situations using Aikido. One of them went from a bartender in college who not only broke up fights, but also was attacked on several occasions, to being a high school teacher who also broke up all of those fights. And he would be the first one to tell you that he has not "mastered" Aikido, and is still gaining new insights into attacks, responses, and techniques.