Translated from the back of the book:
The blade of the heroes of old... Sevenstroke. Ordered by Praios, lord of the twelve gods, forged by Ingerimm and passed to the greatest warrior of an age by Rondra, goddess of war, this weapon is the bane of all demons. Nemesis of the black hordes, a flicker of hope in these dark times and perhaps instrumental in preparing Borbarads downfall.
Yet Sevenstroke has been lost for centuries, and more than a divine quest will be necessary until the god's gift is in mortal hands again...
Sevenstroke is part five of the campaign about the Marks of the Seven and Borbarad's return."
Additional user summary (contains spoilers):
Part 6 of 7 of the campain "The Marks of the Seven" about the return and downfall of legendary black wizard and demon master Borbarad.
In part six the heroes have to find seven magical chalices to reforge them into the divine blade Sevenstroke. During this ritual, this age's champion and bearer of the blade is decided upon.