A resistance braze offers a few advantages over traditional spot welding:
First it allows the joining of materials that otherwise cannot be resistance welded. Generally they are very conductive materials and hard to get hot enough to form a weld nugget. Coppers and brasses would be an example of these.
Secondly a resistance braze can be performed at a lower temperature than a spot weld. We do not have to bring the work piece up to near its melting point. We only need to bring the braze shim to its melting point which is much lower. This means the work piece can preserve some or all of its mechanical properties. Post heat treatment may not be necessary.
The third advantage is that we can control the area of heat application to a small area of the part. We are only heating to a modest temperature and we can protect other areas if desired with cooling. The rest of the part stays strong for the end application.
Reference: CMW Products Inc. Catalog
Tuffaloy Products Catalog
RWMA, Resistance Welding Manual. Section 1, Chapter 6