To cultivating it it's necesary to have a flying sword/saber magic treasure and the cultivator need to be at least at the Core Formation Stage.
After completely cultivating it, when using this divine ability to deal with enemies, one could borrow the sword light from the flying sword to create an illusion of a sword shadow completely identical to the flying sword. This could interfere with the enemy’s line of sight and attack the enemy along with the original sword. Although the sword shadow’s initial formation had only ten percent of the strength of the original sword, as one increased the sword art’s layer, its strength could increase. When it reached the ninth layer, it would have reached one-third of the original sword’s strength.
In addition, when cultivating the sword shadow, one could produce not just one illusion; from the seventh layer onwards, every additional layer one reached would allow one to produce an additional sword shadow.
In this way, once one reached the pinnacle of the Azure Essence Sword Art, one could have three shadows that appeared to be identical to the original sword, yet only had one-third of its strength.