And Esau said unto his father, hast thou but one blessing, my father?.... He seems to speak diminutively of what had been given to Jacob, calling it one blessing: whereas there were many, and of different sorts, both temporal and spiritual; but it may be Esau had not so clear and comprehensive a view of what was contained in Jacob's blessing; or at least was willing to think and hope that there was not so much given, but there might be some behind for him, and that his father had a greater stock than to be drained of all at once:

bless me, even me also, O my father: with another blessing, with one equal to what has been given my brother:

and Esau lift up his voice, and wept; in order to move the affections of his father, and to prevail upon him to reverse the blessing he had bestowed on Jacob, and give it to him; but he could not bring his father to repentance, to change his mind, and revoke the blessing, and give it him, with all his crying and tears, as the apostle observes, Hebrews 12:17.

And Esau said unto his father, Hast thou but one blessing, my father? bless me, even me also, O my father. And Esau lifted up his voice, and wept.

Margin and Esau

Esau wept because of a lost advantage, but "found no way to change his mind, though he sought it carefully with tears" Heb 12:17 so far may regret or remorse be from true repentance:

27:30-40 When Esau understood that Jacob had got the blessing, he cried with a great and exceeding bitter cry. The day is coming, when those that now make light of the blessings of the covenant, and sell their title to spiritual blessings for that which is of no value, will, in vain, ask urgently for them. Isaac, when made sensible of the deceit practised on him, trembled exceedingly. Those who follow the choice of their own affections, rather than the Divine will, get themselves into perplexity. But he soon recovers, and confirms the blessing he had given to Jacob, saying, I have blessed him, and he shall be blessed. Those who part with their wisdom and grace, their faith and a good conscience, for the honours, wealth, or pleasures of this world, however they feign a zeal for the blessing, have judged themselves unworthy of it, and their doom shall be accordingly. A common blessing was bestowed upon Esau. This he desired. Faint desires of happiness, without right choice of the end, and right use of the means, deceive many unto their own ruin. Multitudes go to hell with their mouths full of good wishes. The great difference is, that there is nothing in Esau's blessing which points at Christ; and without that, the fatness of the earth, and the plunder of the field, will stand in little stead. Thus Isaac, by faith, blessed both his sons, according as their lot should be.