Cabosil does decrease the fracture toughness of epoxy, especially if your epoxy system is low on toughness to begin with, as most laminating resins are. You could go with one of the stuctural adhesive epoxies such as Hysol 9396 and get better results. You could also use chopped glass or cotton flock - which is nicer to work with - instead of Cabo. Maybe the best solution is to use 2-part urethane resin. They use this stuff on the leading edges of wood aircraft propellers. It has excellent abrasion resistance and toughness. After mixing, you can put it in a bell jar and apply a vacuum to get the air out. Pour it in place using aluminum tape as a dam. Contour to shape after cure. The result is a beautiful amber-color blade tip with no air bubbles.