In the beta features of V7.83.3b it is said:
Has this ever been released? Couldn't find something about this in the manual. Maybe I'm too blind.
Can I use it by physic-engine, e.g. for a ragdoll?

You can animate a model with another application that supports bone weights (MED doesn't), that means it's a feature for animation, not for physics.

Weights machen Bones-Animationen an Gelenken mit harten Verformungen
(z.B. Kniegelenk) weicher. Dabei können Vertexe mehreren Bones mit
unterschiedlich starker Beeinflussung zugewiesen werden. Wird z.B.
in fragMOTION unterstützt und ist dort gut nach zu vollziehen.

'Bone weights' is a misleading term when you don't mention the vertices, but speak only about bones.
The term 'weight' in this context doesn't mean anything physical, it is a term about the relation between two or more bones and a vertex.
A model with bones with each vertex connected to one bone only(!) has no 'bone weight', a model with the vertex where at least two bones are connected to that vertex and influence the position of the vertex got 'bone weight'.
The influence of the bones can be half and half, but it can be 10% to 90%, or any other ratio, this is meant by weight, the balance of their influence to the connected vertex.

So, I misunderstood the term. Thanks a lot for your explanations.