There are tabs along the top of your backpack, hats robes etc and one of them is for Wands and another is for Athames. Athames do not show up in your hand as an Athame is not for battle use. The Athame's primary use is to direct energy which is why your Athame will increase your stats in some way.
Wands on the other hand, are listed under wands and act like a wand, which means they do show up in your hand and grant spell cards.
You can wear one item at a time from each of the tabs, therefore you can wear an Athame and a Wand at the same time.