It's a fair idea!
Many people arguing that melees dominate reaper. But they don't say which melees are dominating.
So, if these people dont't know (sarcasm on), they are: monks, rangers and vkf rogues. (sarcasm off)
These classes/builds don't need more power!
In the future, the game will be balanced around this buff, and who need this buff "now", will still be far behind.
Edit: Keep the 25% and stacking with stalwart and sacred defense (no armor restrictions),
OR,
keep 25%, non stacking with stalwart/sacred, but working only if using medium/heavy armor (i know that casters can use armor, but still loose power while it active).