Appearance can go a long way to provide characterization. This is because there are visual cues that are associated with certain behaviors or personalities. For instance there's Smart People Wear Glasses, Pink Means Feminine, and Red And Black And Evil All Over. At a glance, these traits provide instant characterization (this person is smart/feminine/evil etc). All this is great for a visual medium like television or a video game but what is a writer supposed to do?
Everything must be described to the reader and no reader wants to read three paragraphs about a character's outfit. This leads to things like Wall of Text and Costume Porn. Thus a writer must be selective with the words they use to give them the greatest effect. This is known The Law of Conservation of Detail; Every detail given is important.
We've all heard of Chekhov's Gun right? It fits with the importance of meaning in someone's appearance. Do not put a parasol into someone's hands on a regular basis unless you want to emphasis a lady-like demeanor, a peculiar choice of weapon, both, or something else. Do not give someone a mantle unless you want to give the impression of a commanding presence,trying to look like they have a commanding presence, some local fashion, all of the above or none of the above. The important thing is that the thing (whatever it is) serves a purpose.
Sometimes this purpose is about appealing to something the audience is thought to like. Tvtropes has many (in my opinion too many) tropes describing such appearance-for-appeal traits. They are organized under 'rules' where the appearance trait (among other things) is included in the work of fiction because the given trait has the given appeal. These rules include The Rule of Cool, Rule of Glamorous, Rule of Sexy, etc. However, even here where the trait's primary purpose is appealing to the audience these tropes can improve characterization by allowing these traits to inform the character's personality or contrasting with their personality.
In my Looming Shadow revision I've used these tropes to highlight contrasts between characters or bring a certain personality trait into focus. I believe it will help the reader immerse themselves in the story. To read more about Painting the full picture, click here