Simon had seen people doing it, the [mana aura] of the ogres and the [mana wings] that the Valkyries used were all an application of emitting your mana out of your body. It was just that those people who were able to do it were all above level 500.
Emitting mana out of one body was totally different than casting magic. The former released non-attribute mana while the latter changed the attribute of the mana into that particular element. Changing the attribute of mana to emit it out was just casting magic, it had nothing to do with mana flow.
What Simon wanted to do was not to emit magic but to release mana from his body without consciously trying to give it any element. It was difficult for Simon because he was used to converting mana into different elements to cast his magic.
He had been doing this from the moment he had learned how to use magic… so it was a tall order from him to suddenly release mana without giving it any elemental form subconsciously.