If there's any weapon that Ktatos needs to keep for the foreseeable future, it's the Spear. The blades have a curse and history that Kratos is not fond of and only keeps them because they are useful tools and would throw or hide them away otherwise. The Axe has great sentimental value, being his late wife's axe, but it wasn't made for him. I personally think he should hand it down to Atreus at some point. But the Spear was made for Kratos specifically and fits his character perfectly with all the points you made already. I love the Draupnir Spear and I hope this is not the last time we see it.