Lei of the Lifegiver

Lei of the Lifegiver is an Alterac Valley Reputation reward that gives the wearer a high bonus to healing.

Source
Lei of the Lifegiver is sold for by one of the Supply Officers for Alterac Valley:
 * Gaelden Hammersmith in Alterac Valley
 * Thanthaldis Snowgleam in Alterac Mountains
 * Grunnda Wolfheart in Alterac Valley
 * Jekyll Flandring in Alterac Mountains

It used to be the case that to purchase this Off-hand, Alliance players had to be Exalted with the Stormpike Guard and Horde players had to be Exalted with the Frostwolf Clan. Reputation is no longer required for PvP rewards as of patch 2.0.