the root isn't "wet", it is most peculiarly "wāt".
The long o is not "the lengthened o-grade of the short e in the ablaut system your author didn't like very well". The long o is the Germanic reflex of pre-Germanic long a. "Wōdinaz" is proto-Germanic, not pre-Germanic. The pre-Germanic is "Wātinos". The difference between the two also drives home the point of making a distinction between pre-Germanic and proto-Germanic. As for the barred d for the proto-Germanic /d/ phoneme, that's just one possible convention for writing proto-Germanic. Take it up with our Proto-Germanic article, we should aim for some consistency across articles. 
As for a source, I agree that Pokorny is just useful for an overview of non-Germanic cognates, not for an in-depth discussion of Germanic etymology. For that, we have the perfectly academic, recent and insightful article by Rübekeil, which has been referenced in plain views since about 2006.  (𒁳)