Hi Bert,
You, William, and I discussed this issue once before in http://discourse.textkit.com/t/pharr-section-128-line-4/547/1
I think it’s safe to say that the dative of interest can also function as a kind of possessive. On this see Smyth 1474-1480. See also Pharr 1000 and Iliad 1.150 whence Pharr 248.7.
Cordially,
Paul