Well i may be reading it wrong ... wouldnt be the first time.

But it clearly says "you" deal an extra 1d6 necrotic damage.

Also as far as i know, Hex should most certainly not in any way affect your hit chances. O_o
Correct, the extra necrotic damage helps Wyll but not others!
However, I didn't mean to indicate that it helped my hit chances, only that it lowers the Wisdom saving throw when I use Dissonant Whispers or Tasha's Hideous Laughter my two favorite Bard spells.