Level is irrelevant here. Dive into a R38+, check the bonus list and all enemies on every floor, and pray. You will find a legendary R39 eventually, and then you can dive into that to increase your chance of finding other legendary R39 equipments.

I think it is a factor . I seen a screenshot with a 2000 lvl enemy with it. When the world gets weak and easy I get nothing. Boost world and get an infernal staff but not a match. All my star shatters are lvl 20.

Enemy level is a factor for what equipment they come with, item rank and item level are factors for what appears in the bonus gauge... and luck is a factor for both. Anywhere you can find r39 items, you can find a legendary God's Hand.