The factor is, Din didn’t understand the weapon’s particular significance. So his new-ish ally Bo-Katan Kryze—the sister of Clone Wars’ Duchess Satine, the previous ruler of Mandalore, and herself the temporary chief of the Mandalorian resistance earlier than the Empire ravaged the planet—is livid that he has it, as a result of the one method she will be able to now honorably purchase it herself is to defeat him in ritual fight, which Din does not wish to occur. So her personal plans to return to Mandalore and rule her individuals have been upended.
Additionally, he retains slicing himself open attempting to make use of a lightsaber he doesn’t know the right way to use, so there’s additionally that. He’s not even proud of himself!