From Proto-Indo-European word *nepōts (Latin nepos, Sanskrit napāt) I need to determine what is its cognate in Old English. More precisely, I need to determine whether the result is nefa (Grimm's Law) or neba (Verner's law).
So as far as I know, if the stress is preceding the p in *nepōts, the result is nefa. If not, the result will be neba. But how do I know which syllable is stressed in Proto-Indo-European? Does the length on the o mean that the primary stress isn't there? Or that it is?