Other translations like NET gives better understanding of the verse,
"How delightful it is to see approaching over the mountains the feet of a messenger who announces peace, a messenger who brings good news, who announces deliverance, who says to Zion, “Your God reigns!”
John gill on that verse says
"How beautiful upon the mountains are the feet of him that bringeth good tidings,.... Not of the messenger that brought the news of Cyrus's proclamation of liberty to the Jews; rather of John the Baptist, the forerunner of our Lord; best of Christ himself, the messenger of the covenant, who was anointed to preach glad tidings to the meek, and by whom grace, peace, life, and salvation came; and also of the apostles of Christ, for to Gospel times are these words applied, and to more persons than one, Ro 10:15, who were not only seen "upon the mountains" of the land of Israel, as the Targum paraphrases it, where both Christ and his apostles preached, but upon the mountains of the Gentile world; and may denote the pains they took, the circuit they made, and the difficulties they had to encounter with; and the publicness of their ministrations, which lay in bringing "good tidings" of the incarnate Saviour, of God manifest in the flesh, for the word k here used has the signification of flesh in it; of good things in the heart of God for his people, in the covenant of grace, in the hands of Christ, and as come by him, and to be had from him; as pardon by his blood; justification by his righteousness; eternal life and happiness through him; and of all good things to be enjoyed now and hereafter. It may be applied to all other ministers of the Gospel in later ages, who are bringers of the same good tidings to the children of men, to whom their very feet are beautiful, and even at a distance, upon the high mountains; not to carnal men, but sensible sinners, to whom the good news of salvation by Christ is welcome. Feet are mentioned instead of their whole persons, because the instruments of motion, and so of bringing the tidings, and of running to and fro with them from place to place, and even though they are dirty and defiled with sin; for Gospel ministers are not free from it, and are men of like passions with others; yet are beautiful when their walk and ministry, conversation and doctrine, agree together; and their feet are particularly so, being shod with the preparation of the Gospel of peace. The words may with the greatest propriety, and in agreement with the context, be understood of that angel, or set of Gospel ministers in the latter day, represented as flying in the midst of the heavens, having the everlasting Gospel to preach to all nations, which will precede the fall of Babylon... "