Kensei’s Sharpen the Blade: can it work for weapons like Flametongue or Frostbrand?

@JeremyECrawford @SageAdviceDnD Kensei's Sharpen the Blade: can it work for weapons like Frostbrand or Flametongue, or does the +d6 extra damage violate under the "no magic weapons that have an attack and damage bonus" bit?

— James Harmon (@harmonjames) December 22, 2017

Sharpen the Blade works on a magic weapon, such as a flame tongue or frost brand, that lacks a bonus to attack and damage rolls. #DnD https://t.co/H2x1i0PBPl

— Jeremy Crawford (@JeremyECrawford) December 22, 2017