This edition builds and refines the rules presented on the 4th edition, published 19 years ago. Sections on medieval society are greatly expanded, taking advantage of two more decades of historical research.
Judaism and Islam join Christianity in the core rules for the first time, with sections written by members of those faiths who have studied medieval beliefs and practices. Guidelines for creating fantasy religions and pantheons are included.
Alongside fantastical magick, an optional system presents magick from the medieval worldview.
Disclosure: I am involved in designing this edition.
I absolutely reccomend Bob's games. Although changing work circumstanes forced me to drop out his games were always fun and the group, at least back then, rotated through different games/GMs often enough that things never got stale.