Splinter property cannot be imbued.
Splintering works the way it sound, a small piece of the weapon creates a bleed effect on the target, causing the item to lose durability at a very fast rate.
Splintering + Brittle is the worst combo because you cannot repair it ( but you can use PoF ) , so it will break rather quickly.
As already mentioned, Splinter + Brittle is not Worth alot.