Wizer makes an appearance for the first time in a Slayers Special novel, then again in volume 10 of the main novels. In the second case, when Lina and Gourry are in Solaria, Wizer appears in a mask to rescue them multiple times. His identity is not revealed until the end.
In Slayers REVOLUTION, Wizer at first glance seems to serve as the comic relief of the series. However, he is actually quite intelligent and schemes well (except when he took Xelloss's advice in episode eight). He also displayed some physical and personality similarities to Xelloss; most notably, his eyes are rarely open, and when they are, are shown to also have little to no light in them, portraying a rather sinister face to match his underlying cunning disposition. He also seems to have a tendency to withhold information or manipulate others if it will serve to achieve his goals, much like Xelloss does, though his intentions are mostly for a noble cause. The key difference in their manipulation techniques is the fact that the mazoku priest always avoids telling a lie, while Wizer lies readily, sometimes to a ridiculous extent.
Wizer first appeared in episode 1 of REVOLUTION, where he tried to arrest Lina Inverse "for being Lina Inverse." He was investigating the destruction of the mage-tanks of Ruvinagald, and suspected Lina was the culprit. However, the tanks actually being destroyed by Pokota, the designer of said tanks and a magic user on the same level as Lina herself.
His stated reason for his single-minded fervency was to impress the ladies of Ruvinagald's court. It is later hinted that Wizer may have been assigned to investigate what happened to the aid relief meant for the Taforashia kingdom that disappeared, or if he wasn't he'd been looking into it. Regardless of the circumstances, he was intelligent enough to suspect and confirm Gioconda's guilt, to even Xelloss' surprise. While he wasn't a participant in the final battle of Slayers REVOLUTION, he was a key witness, as he knew that even if he tried to help the Slayers he would only end up getting in their way. He was last seen speaking to Xelloss as they watched the battle unfold.
Wizer shows little battle prowess in the anime, but in the novels, he displays remarkable skill fighting bare-handed, and also seems capable of holding his own when it comes to spells.