Fine Now
If Leonel hadn't managed to separate his soul from his body, he would have never taken this approach. The first part of fusion technique wasn't even the most masochistic part about it. What was truly the most sadistic part of this technique's creator's intentions was what came next.
After the connection was formed with the Innate Node, it was necessary to graft the Innate Node into your body. But in order to succeed, it required a special process which was akin to branding your own body. But this branding would have to be from the inside and rather than using fire, it required blades.
Only by purposely scarring oneself would the fusion be perfect.
Essentially, Leonel had to cut into his own brain stem. The pattern of these cuts had to match with two Force Arts he used to refine his blood with. The more sensitive the region, the more difficult it would be to succeed, but this was the price to pay for success.