'Skill' is Old Norse for 'discernment' — from PIE 'to cut.' Knowing was cutting things apart to tell them from each other.
The ability to do something well; expertise or dexterity acquired through training or experience.
From Old Norse 'skil' meaning 'distinction, discernment, knowledge,' which entered English during the Viking Age. The original Norse meaning centered on the ability to distinguish and discriminate — to tell things apart — rather than manual dexterity. The semantic shift from 'discernment' to 'practical ability' occurred gradually in English over several centuries
In its earliest English usage, 'skill' meant 'reason' or 'the power of discernment' — you could say something 'lacked skill' to mean it was unreasonable. The modern sense of practical expertise did not become dominant until the sixteenth century, a full 300 years after the word entered English.