The Soul Knife’s Blades also benefit from the 1d8 additional damage all the other weapons do as a part of the Mystic base class. At level 14 you are looking at a 3d8 + 5 (DEX) + 3d8 (Bonus Attack) for some decent every hit kind of damage.
Now stack on to of that Hone the Blade: 3d8 + 5 (DEX)...
