i feel like u missing the something in the story she is not useless at all u know read the update chapter she give blessing to the hero and his party like that or she trying to change her life ( that actually hard) if u trying to say she cant fight like a real saint tell me what shes doing in her whole life?(in past and present?)
when you said you didnt say if shes weak or strong. think you misunderstood. The Physically word has a lot of meanings. Lets remove the whole imagine part so it wont look like its about power or how strong person she is. She dont do anything physically but something metally. She use words instead of actions. Although that often lead into danger. Thats why she looks useless. (〜 ̄△ ̄)〜
If i misunderstood. Can you please give me the detail. What kind of "useful" are you talking about? ╮( ̄▽ ̄)╭
And also;
the story is not done yet. We cant say if she is useless in the "whole story". Lets just wait untill it ends. If she doesnt do anything at all UNTILL THE END. We can confirm that shes pretty much useless. (⌒▽⌒)
(Sorry, just to make it clear)

Louisa is useless