Just to add to the pile of ambi comments, I foolishly went ambidex fighting from the very start of my larping career (which is now so far in the past that I don’t like thinking about it) Despite the fact that I enjoy it as a fighting style, I’d advise against it in Empire, and doubly so for a battlemage.
The short version is that ambid is useful in one on one duels, (where you can take advantage of the fact that you can attack with either hand) or in skirmishes where you need to hold off a wide angle of attack and may be potentially fighting vs 2 people simultaneously.
What is really really isn’t good at is formation fighting, line fighting or pitched battles in wide open spaces. Or against spears. Or shields. It absolutely sucks againsts multiple people with spears/shields. You get the idea.
That’s not to say that you can’t win those match ups, but it’s nowhere near as easy as with other combos, and that’s even before we start to discuss the joy that is Empire’s insta kill arrows.
My advice would be to start out with a rod and buckler, borrow a staff or shield from another member of your group for monstering to try out the combat style and then either go offensive (staff) or defensive (shield) as you find comfortable. Even if you have insane combat skills, you’ll find either weapon set up superior to duel wielding in terms of keeping you alive.