It is very simple to Unrust the blade. You have to keep it in the bowl of vinegar for 24 hours. The acid in the vinegar will extract all the iron particles from the blade and make it clear.
Then use the steel wool or sandpaper and rub it on the blade in order to remove the remaining particle. In the end, wash the blade thoroughly with water.
Let it sit so that it gets completely dried. In the end, apply the layer of olive or linseed oil and place it inside the sheath.