My artificer has both a Wand of the War Mage and the Enhanced Arcane Focus infusion, but I can't apply this infusion to this wand. I haven't found anything to indicate that I shouldn't be able to, but the infusion will only let me select a generic wand, staff, or rod, even if I've already attuned to the Wand of the War Mage.

Infusions can only be applied to non-magical items, so the Wand of the War Mage is off limits.

Whenever you finish a long rest, you can touch a non-magical object and imbue it with one of your artificer infusions, turning it into a magic item.

🤦‍♂️