Warrior talent · row 2 of Protection, from level 15 (10 with Talented 5/5) · Physical

Improved Revenge

Increases damage dealt by your Revenge ability by 20/40/60%.

Game files · build 1.60.1.70245Read from the WoW Forever beta client, build 1.60.1.70245.

Compared with Classic

Classic tooltip

Gives your Revenge ability a 15% chance to stun the target for 3 sec.

What Blizzard said about Improved Revenge, each line checked against the files.

Matches the files
Improved Revenge moved to Row 2 (Was Row 3).
The files The Oct 2 server hotfix (read from the 70245 client cache) moved Improved Revenge's node (105969) from row 3 to row 2 (PosY 3330 to 2730).
Improved Revenge Development Notes, October 1
Matches the files
Improved Revenge moved to Row 2 (Was Row 3).
The files Row 3 to row 2 in the 70245 hotfix (PosY 3330 to 2730), spell 12797.
Improved Revenge Warrior updates, October 2
Matches the files
Improved Revenge: (Redesigned.) Now increases damage done by Revenge instead of a chance to Stun the target.
The files Classic gave a 15-45% chance to stun; 70245 adds 20/40/60% Revenge damage (spell 12797).
Improved Revenge Class deep dives: Priest and Warrior

69876 Sep 16First beta build we archived. No changes in the client files since.