The two biggest problems I see with the Mosaic runeword are the following: 1. The unique effect is tied to an item rather than a skill; and 2. All martial arts assassins now duel wield Mosaic, limiting build diversity.
In order to solve these problems I propose that Mosaic’s unique effect be given to Claw Mastery and the chance to proc reduced on the runeword. With 1 point +skills +1 Mosaic the effect should have a high chance to proc. With 20 points +skills and no Mosaic the effect should have a high chance to proc. This would open up weapon slots and provide build options.
For claw diversity generally, I propose that the Crescent Moon and Lawbringer runewords be extended to claws. Lightning trapsins could now make Crescent Moon in runic or greater talons rather than phaseblades. In order to dual wield they would need to sacrifice Spirit. Bladesins could now make Lawbringer in ethereal suwayyahs, competing with Plague for best in slot. In time perhaps a viable two to three socket fire runeword could be added to the game.