what im interpreting from this is that miyos saying that the most important thing in sumo and in fighting in general, is that you need to have a clear idea of who you are and what you want to do in the battle before it begins. not so much as i need to do xyz, but more along the lines of being truly satisfied with urself and ur motives inside and outside of the fight.
he said that maki has been made "captive" by something, and whether that be curses, humans, or herself, i think it centers around the idea that maki is limited by the idea of what she "should" be or rather rigid in her understanding of the world around her. like how the katana said he doesn't need to see the curse directly, if he can see everything but the curse; it's practically like he can see it. i think miyo's teachings are following that same sort of mentality. even if maki can't see the world around her clearly, from fights to general philosophy, as long as she can see herself clearly, thru time, she'll be able to see all she can't see, because she can see everything but it.
the metaphor i also think for that is like how light and dark works. if something is dark, there is no light. if something is light, there is no dark. if something is not maki, it's not her. and so she'll take what she does know herself, and use it to "experience it [the unknown] with her own body."
the main emphasis here seems to be in having a strong sense of identity and purpose, one that won't be wavered by senses or circumstances, a rigid model by which you can gauge the rest of the world. and that is the true "freedom" here a self that is free from being defined from the world around it, she'll use herself to define the world around her, the inverse of katana using the world around him to define the spirit. maki will define the world herself
anyways i need maki to marry me