Mauro and Jean
As for comparing TSUBA and trying to determine their lineage, I am always grateful to that great early collector Bashford Dean- his quote
"Let him but try to classify these tsuba before him, and he will find how complicated is his task. Most of us would not attempt it, but he who is thoughtful will long be haunted by the problem which he cannot solve: try as he may to distinguish clearly the groups of sword guards, he will ever find that his criteria "interlock" inextricably. Thus he may try in vain to classify his guards according to their material, whether finished or roughened, whether perforated or plain, whether smooth, encrusted, or inlaid; or according to subjects; or, if he follows his task more thoroughly, even according to the "schools" of the artists who created them." The Metropolitan Museum of Art Bulletin. Vol. 16, No. 7 Author: Bashford Dean 1921
This allows me to sleep at night when I can't assign a particular piece !