Wanding something refers to the action of attacking a target with a wand, staff, or spear, typically by a caster in between spells or a warrior trying to build adrenaline from afar. Wanding is used to finish off a target who is practically dead, trigger the effect(s) of certain enchantments like Reversal of Fortune and various hexes such as Mark of Rodgort, or to interrupt trappers as well as dazed targets.
Note that wands, staves, and spears (@ 0 Mastery) deal negligible damage at a slow attack speed, with medium range, medium accuracy, and a near-zero critical-hit chance. Thus wanding is impractical and ineffective if one is aiming to apply pressure, and therefore a caster (especially a caster) would be doing much more good to both the player and the team by continuously moving (kiting) on his/her toes and observing the battlefield with his/her eyes.