The Hebrew that is translated as “his eyes are darker than wine” or similar in English is translated in Kutu as “his eyes are redder than wine.”
“To say someone has ‘dark’ eyes here is a very negative thing. (…) [Here it is understood] that they are talking about abundance of wine and milk and people eyes are bloodshot from drinking much wine and the teeth are healthy from much milk.” (Source: Pioneer Bible Translators, project-specific translation notes in Paratext)
See also beautiful eyes and blind.
Following are a number of back-translations as well as a sample translation for translators of Genesis 49:12:
- Kankanaey: “The color (kolor) of his eyes, it is better/nicer than the alcoholic-beverage of grapes. His teeth also, (they) are whiter than milk.'” (Source: Kankanaey Back Translation)
- Newari: “His eyes sparkle more brightly than grape juice, his teeth seem whiter than milk.” (Source: Newari Back Translation)
- Hiligaynon: “Therefore in excessive drinking of drink your (sing.) eyes will-become-red and in excessive drinking of milk your (sing.) teeth will-become-white.” (Source: Hiligaynon Back Translation)
- English: “Their eyes will be red because of drinking too much wine, but their teeth will be very white because of drinking much milk from the cows.” (Source: Translation for Translators)