User blog comment:B214/Gray power up analysis/@comment-24546844-20141214133817/@comment-31.61.140.220-20141214173119

I don't equate them. They are just examples that magic can be "just received," although the scale is different.

About Auquarius's magic - we don't really know if it's permanent or not, but we don't know it about Silver's magic either. Also, it was said in this chapter that not only Silver's magic was passed to Gray, but his soul were "carved in his son body" - at least that's what panda's translation said []. So, the argument can be made that it is also Silver casting magic through Gray, similar to what you said about Aquarius.