Have you tested this with Zaws yet? I'm noticing tiny but weird discrepancies in slash proc damage with both Gram Prime and Nikana Prime with speed mods on/off, but for some reason my Zaw (or at least its slash procs) seem unaffected. Non-gilded, non-catalyzed Sepfahn strike Zaw at rank 20 with Korb grip and Vargeet II Ruhang link. Tested on level 100 Nox with AI on. Bit late where I am so afraid I can't test this much yet. Using the heavy attack on Nikanas to force the slash proc.