I think the way the sharigan works is that, the user can copy all techniques excluding blood line limits. However they must fill the conditions of the tecniques to use them, for example have a fire affintiy to preform a copied Fire Release: Great Fireball. So even if Kakashi can copy the Blade of Wind technique for example, he wouldn't be able to perform because he doesn't have wind affintiy. I hope that clears it up.