Or you could lash a rock at it at very high speeds and just kill someone with impact damage, or soulcast oil above them and burn them to death or use division to create lightning or sneak attack to get behind the shield with a Lightweaving, or abrasion the ground so that they can't hold the shield up, or use a number of other tactics. A Al shield is actually a pretty useful equalizer especially if accompanied with armor and insulated padding but if you let one guy have specialized weaponry then the other one gets it too and I don't think you really do anything beyond making the fights more about brute force and less about magic and tactics. In a brute force match up radiants with plate still win.