신명기 7:14 주석: Rashi, Or HaChaim, Rashbam & Rabbeinu Bahya

עקר means, a man who cannot procreate.

ברוך תהיה מכל העמים, "You will be more blessed than all the nations." This can either mean that there will not be a nation which is greater in stature than the Jewish nation, or it could mean: ברוך תהיה, "you will enjoy certain blessings over and beyond those enjoyed by other nations;" what are these blessings? "There will be none amongst you that are barren genetically." Beyond that, "if there is someone amongst you who has become barren through sickness, G'd will remove this sickness from you, etc." It will thus become common knowledge that you have been blessed by the Lord your G'd.

עקר, with two vowels kametz. Other examples of such constructions are חכם as opposed to אשה חכמה, (Samuel II 14,2) or שפל as opposed to ושפלה איננה in Leviticus 13,21. I have found that all the texts published in Spain follow this vowel pattern. [remember that our author was Ashkenazi. Ed.]