Matthew Poole and continuators on Deuteronomy 33:25

25 Thy shoes shall be iron and brass : and as thy dayes, so shall thy strength be .

This may note, either 1. Their great strength by which they should be able to tread down and crush their Enemies, as Christs feet for this very reason are said to be of brass, Revel. 1. 15. Or 2. The mines of Iron and Copper, which were in their portion, whence Sidon their neighbour was famous among the heathens for its plenty of brass, and Sarepta is thought to have its name from the brass and iron, which were melted there in great quantity. Compare Deut. 8. 9. Or 3. The strength of its scituation, and so some antients and moderns render the words, thy habitation or thy enclosure shall be iron and brass, i. e. fortified as it were with walls and gates of iron and brass, being defended by the Sea on one side, by their brethren on other sides, as also by mountains and rivers.

(i. e.) Thy strength shall not be diminished with thine age, but thou shalt have the vigour of youth even in thy old age: thy Tribe shall grow stronger and stronger.

Marginal references: Or, under thy shoes shall be iron.