Warrior talent · row 1 of Arms, from level 10 (5 with Talented 5/5) · Physical

Deflection

Increases your Parry chance by 1/2/3/4/5%.

Game files · build 1.60.1.70291Read from the WoW Forever beta client, build 1.60.1.70291.

Compared with Classic

Classic tooltip

Increases your Parry chance by 1%.

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

Matches the files
Deflection: Now grants twice as much Parry chance per point.
The files Deflection (13713) gives 2/4/6% Parry over 3 ranks; Classic gave 1% per point over 5, so the top value went from 5% to 6%.
Deflection Class deep dives: Rogue and Warlock

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