This is just a little theory with only a little evidence.
Let's see, what makes an Unversed? Negative Emotions. Now, what would I consider negative emotions? Anger and Hatred. Where have we heard this before? "Anger and hate, are supreme." said by Xemnas. Maybe Xemnas was right, in some way. If Xehanort was an unversed he would be made of negative emotions. Which Xemnas seems to really like. Maybe if negative emotions in someone are very strong (Terra's feelings towards MX) than an unversed would be a very strong one i.e a very humanoid one. Similiar to if a heart is very strong a strong nobody might be created i.e Organization XIII well idk I just connected to how Xemnas was talking about negative emotions are stronger in a heart than other emotions and unversed are made up of negative emotions
Let's see, what makes an Unversed? Negative Emotions. Now, what would I consider negative emotions? Anger and Hatred. Where have we heard this before? "Anger and hate, are supreme." said by Xemnas. Maybe Xemnas was right, in some way. If Xehanort was an unversed he would be made of negative emotions. Which Xemnas seems to really like. Maybe if negative emotions in someone are very strong (Terra's feelings towards MX) than an unversed would be a very strong one i.e a very humanoid one. Similiar to if a heart is very strong a strong nobody might be created i.e Organization XIII well idk I just connected to how Xemnas was talking about negative emotions are stronger in a heart than other emotions and unversed are made up of negative emotions