I love Marston, but there are a lot of things he did that could still be done better.
The Golden Girdle already has clear powers, making someone invincible. That power has nothing to do with what the lasso does.
And it seems to me like a missed opportunity to tie up this fascinating and thematic part of the Greek Myth of Moriai / Fates that determine a person's life through glowing threads that they weave, and Diana having a glowing lasso that can enter a person's soul and discover hidden truths. Feels to me like a perfect connection. And the idea of Diana literally taking fate into her own hands, and using it as her "weapon" to change the world, seems ro me very symbolic of who Diana is.