"Jesus Christ, Himself, could send a bar of steel down from Heaven.
It will only be as good as the heat treatment it gets."
Jerry Rados.
Nickel doesn't make 15N20 or your Damascus softer.
Think of it this way, that 15N20, made by Uddeholm, is the very same stock used to make industrial/commercial bandsaw blades for saw mills that cut MILES! of logs and timber before being resharpened or replaced.
Using known steels, any failures we encounter can not be blamed on the steel.
5160 will make a tougher blade - possibly, because of the chromium carbides - but 1084/15N20 pattern welded steel should get sharper and potentially stay that way longer.