So I feel like this item is never worth using, in any case. To me I don’t get why the 80 ward cost to reset the duration is a thing, when you can just recast fire shield before it expires. It’s other stats are fine for a low level character, but you can pretty quickly craft a much better item.
Make Fire Shield last forever, but have less mana efficiency or mana regen.
Give a general fire aura, instead of the interaction with fire shield specifically, but have less ward retention. That way other classes can use the shield too. (Idea from LiquidOxygen)
Whenever you cast a fire spell you ignite yourself, but also adds a 100% ignite chance.