Bless You!

Moshe blesses the people of Israel including all of the tribes except for the Shimonites. This, explains Rashi,was because he was still angered at what the Shimonites had done with the Midianite women.
There had been several tribes that had challenged Moshe's leadership, yet Moshe found it within him to bless even them. Yet when it came to the Shimonites he could not bring himself to bless them.
The lesson is an awesome one. All sins can have a time to be overlooked and forgotten. The sin of intermarriage with the subsequent loss of Jewish identity has no way of being overlooked!
Yet here we talk of the survivors of the episode. Surely Moshe could have blessed them ?
We must conclude that the nature that turned the Shimonites into becoming enticed en-masse,
was a general defect that had to be corrected . Had Moshe blessed the surviving Shimonites they would have assumed that they need not look into themselves regarding this weakness as they hadn't sinned as their unfortunate brothers did .
By withholding an open Blessing for them , the Shimonites were moved to do Teshuvah.
The question then turns to identifying the element within Shimon's character that could have affected all of his progeny . What could it have been ?
This requires one to declare at the onset that the Tribes were so much of a higher nature than ourselves that we cannot possibly compare ourselves or hope to truly fathom their thoughts. Nonetheless, the fact that Shimon more than any brother was jealous of Yossef and wished him harm, reflects upon an insecure and unsatisfied nature. Unhappiness and jealousy make for the kind of environment where one is easily enticed by someone offering care and pleasure.
Through the 272 years since Joseph's sale into slavery the Shimonites had not progressed in this area.
For this reason they could not be singled out for Blessing as the nature that made them dissatisfied had to be uprooted first.