This little scene telling how Wentworth saved Benwick from suicide is very affecting.

"The Laconia had come into Plymouth the week before; no danger of her being sent to sea again. He stood his chance for the rest -- wrote up for leave of absence; but without waiting the return, travelled night and day till he got to Portsmouth, rowed off to the Grappler that instant, and never left the poor fellow for a week. That's what he did, and nobody else could have saved poor James. You may think, Miss Elliot, whether he is dear to us!"

Wentworth is a staunch and true friend. But... he left his ship without waiting for confirmation of his leave. He was, essentially, AWOL.

The combination of traits - loyalty, friendship, etc - along with an almost reckless impetuousness takes the breath away, this vividness and larger-than-life aspect to Wentworth. But, isn't this trait just what Lady Russell objected to eight years ago? Wouldn't she be horrified to think that he risked his command by leaving as he did? Do you think she read him correctly all those years ago? Was she right to think it dangerous? It appears he hasn't changed.