The cost is too high, the risk even higher. Generally, a cultivator can only refine one outer body incarnation, doing more would damage the Nascent Soul, risking the foundation's collapse, and being not worth the loss.
But Shen Hex is no ordinary person, his Daoist Nascent Soul foundation is profound, and this Demon Saber Dao Sword is also his life-bound weapon. Refining it costs less and is less difficult; creating two outer bodies is not hard and poses no threat to the foundation.
This outer incarnation can not only substitute in dangerous tribulations and handle dirty work but also aid the original body in cultivation, yielding twice the results with half the effort. When necessary, it can merge back with the original body, elevating cultivation and strengthening the foundation.
Thus, whenever possible, Nascent Soul cultivators will refine outer body incarnations. The Celestial Slaughter Demon Monarch is an example.
