D&D 5E Homebrew Feat: Dueling Mastery

[Warmaster Horus]

The Sharpshooter feat provides benefits even if you don't use the -5 to hit for +10 damage - you don't get Disadvantage at long range and you ignore half and three-quarters cover.

Yep. It definitely helps make throwing darts very dangerous in the hands of an assassin in a crowded bar (ask me how I know... :>). Do you want to make that a separate feat(s)?

 

[Celtavian]

Isn't there a guideline in 5E that the specific overrides the general?

There is a guideline that specifies bonuses from the same source don't stack. Didn't say anything about penalties replacing bonuses or not stacking.