Hey @13udo! To my knowledge, this is not something you can do. Planar tracking and 3D camera tracking are different in the way they work at the core. I am not an avid Fusion user so someone else might have better input on this but I would look into object tracking. Object tracking is going to help you track an object, in your case an arm, in 3D space. You can then use those results to animate the blade.
Are you using a 3D model of the blade or is it a 2D element?
In principle Zac is right, that you can’t combine them directly, but there are usually ways to do things in Fusion in multiple ways. If you have both a moving camera and a moving arm, then things will be more difficult by default, since you have two moving parts. Any chance you can share the shot, so we can provide you with better suggestions?