Legend of the White Fang

Kakashi strikes down the opponent with Sakumo's White Light Chakra Sabre and goes through them with Chidori, causing a lightning explosion. Kakashi had mastered the jutsu in quiet a young age. At that time Kakashi having not developed Lightning Cutter is said to have used Chidori instead. It may be that if the White Light Chakra Sabre would do the same attack with Lightning Cutter, it would be a lot stronger.