] Charecters like Wickham and Lizzy attest to Lady Catherine's authoritive air and self-importance yet she does not seem a formidable charecter.

Lady C is not a formidible character to Lizzy because Lizzy doesn't give her that power. But Lady C does have a different effect on people who are awed by her title and wealth, like Sir William and Maria. And, I imagine, her tenants. I wouldn't care to be a tenant of hers that she did not consider sufficiently prosperous or harmonious.