From the Kingdom Hearts Wiki: A world of information not accessible by Gummiship
Finish (フィニッシュ, Finisshu?) is a Finish command that appears in Kingdom Hearts Birth by Sleep. It allows the user to execute two extremely fast back-and-forth sets of cross slashes followed by a powerful overhead spinning strike, although the version used by Ventus's D-Link uses only one set of cross slashes and the final strike.
Kingdom Hearts Birth by Sleep