In the first half of the 15th century, swordmaster Sigmund Ringeck compiled a book with comments on the fencing teachings from Johannes Liechtenauer's verses from c.1389. (Master Sigmund Ringeck's Commentaries on Johann Liechtenauer's Fechtbuch - c. 1389 to 1440)
Ringeck's longsword style is very simple and yet elegant in its approach, based on efficiency and simplicity. While many of the Medieval fighting manuals primarily show counter-techniques and tricks, Ringeck's greatness is that he starts with the basics and then step-by-step teaches the student the secrets of the longsword.
David Lindholm has an excellent on-line introduction to Ringeck as well as a book, Sigmund Ringeck's Knightly Art of the Longsword, the first in a series on Medieval martial arts, available from Paladin Press.
Oakeshott describes the Type XV as a strongly tapering, acutely pointed blade of flattened diamond cross-section. The sub-type XVa is often longer and slimmer than the Type XV, but with the primary difference being the longer grip. This type of sword was referred to as an epée bâtarde or "bastard sword."