My own take on fighting as a battle mage. A shield can help with not dying. But as you don’t wear armour, being close to the enemy is bad. As is being slower. Shields cause both these things. Staffs keep you fast and out of the reach of most enemies in my opinion. though not if you are planning on holding it by the middle all the time, other issues with this darth maul style of combat would be that you have to keep both hands on the staff at all times and both hands must be atleast 18 inches apart. So I’m not saying don’t do it… but if you are aiming for effectiveness then it’s putting yourself at a disadvantage.
As for the crystal implement, if it was more octangular and didn’t have such a ‘sword’ looking cross guard then maybe it would work.