en_tn_condensed/isa/22/22.md

I will place the key of the house of David on his shoulder ... none will open

Here "key" represents authority. This speaks of Eliakim having authority that no one can oppose as if he had the key to the palace and no one else could lock or unlock the door. AT: "I will put him in charge of those who work in the king's palace, and when he makes a decision no one will be able to oppose him" (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-metaphor)