I think the design is a bit weak on all the knock-off brands. The size of wood it will cut before breaking depends on how good the crimp was made, so I think it’s sort of “pot luck” with these things.
That said, I fixed mine and used it last year with excellent results. It produces perfectly matched cuts which heal like ramv’s photo above. So far I’m much more satisfied with the fit and success than grafts I’ve done with a knife or double blade pruners.
There is a parallel thread about this tool where I showed how I repaired mine. Mine was a fairly extensive repair I explain toward the end of the thread, but @danchappell had an much easier home fix repair in post number 28.