John Wesley on 1 Samuel 21:9

Ephod - That is, behind that holy place allotted for the keeping of the sacred, or priestly garments; all which are here comprehended under the ephod; which, as the chief is put for all the rest. Here it was laid up as a sacred monument of God's power and goodness. None like it - Because it not only served him for his use, for he was a strong and tall man, and one that could wield that sword, but was also a pledge of God's favour to him. Whenever be looked upon it, it would be a support to his faith, by reminding him of what God had already done.