How to hold deformation for a group of vertices?

I am (noob )) ) experimenting with animating organics. In this case, the tail of a reptile with a spike (concept, sorry). I cannot stop the rigging deformation of the area near the spike and skin junction. It looks ugly. Need help. Thanks.

Give all the vertices making up that structure the same weights.

Same problem. Sorry.

Sometimes it’s easier to detach parts of the mesh rather than working with one huge object.