i-S 111 dink finish

[Enrick]

Hi team I have just repaired a couple of breakages on the right edge (in the reduced width tail area) of my 111lt wood 2010 i-Sonic. I tried to make the edge really flat to copy the same line of the left one and I retrieved a good result but my question is about the finish: I finished it with a #600 sandpaper and polished with grinding paste ->at touch it seems really slick, in order to have best fluency can I leave it unvarnished or I have to varnish it? Is there some specific requirement on the finish to avoid attrition and if I would use grinding paste on all the board could I improve the fluency comparing with series varnish?
Thanks,
Best regards
Enrico