Do what every successful business has ever done with hard to crack problems: outsource it.
In order to outsource the problem of hot wands, you will need:
- feathers
- a bow
See a picture below of some witches invoking some explosive fireballs (you know, the kinda that goes boom when it hits something). Notice that they are grasping the wand firmly with the right hand, while grasping the bow with the left hand.
Once the wand flies, the issue has been successfully outsourced to whomever you were aiming your fireball at. Any heating concerns are now SEP's (Someone Else's Problem).
And before you tell me that goes against the melee usage rule: you can use an arrow on a melee fight if you really want to.