This is a little weak aura that reminds you to equip the Blade of Wizardry when its off CD and your other main hand while it is on CD.
Main hands can be swapped in combat. Feel free to adjust my macro below which swaps between my blades:
/equip Blade of Wizardry
/equip Bloodmaw Magus-Blade
Automatic equipping while in combat is not supported.