[Make way, fellow nerd coming through. Her own comm blinks on, she's sitting in front of it studiously taking notes on Sam's proposals. Typing is too damn hard, okay.]

I have found holy water to be ineffective, generally, unless used in a larger ritual context. However I can vouch for the effectiveness of salt in wards - although not for what I would properly call a wraith, following the proper differentiation between wraith and spirit that I am familiar with. Those require powdered stone from a tomb. Unfortunately I doubt anything here will hold still long enough for us to test the differences, more's the pity.

You're well versed in supernatural weaknesses. Are you a hunter?