What does “let alone brain anybody with” mean? [closed]

Yet another a part of Circular Staircase, by Mary Rinehart:

"Not out in the hall!" she gasped; "Oh, Miss Rachel, not out in the hall!" trying to hold me back. But I am a large woman and Liddy is small. We got to the door, somehow, and Liddy held a brass andiron, which it was all she could do to lift, let alone brain anybody with. I listened, and, hearing nothing, opened the door a little and peered into the hall.

Are any words omitted in the sentence that includes let alone brain anybody with? Something looks missing from this sentence.

To "brain" someone is to hit them on the head, usually with some sort of heavy object. The implication of the quote is that Liddy would not have been able to use the andiron as a weapon.