Argue it if you like, as it is your story. However the reality is an adult, british male (and pureblood wizard) would only use the word 'Whoa' when riding a horse (or equivalent). "Good heavens!, Great Merlin!, or even a "My God!" would be a more likely exclamation, and is less likely to jar your reader out of the tale you are telling.
The thing you perhaps want to keep in mind is that your reader isn't interested in looking at the pattern of the wallpaper in every scene, so if you describe it once, there's no point describing it again every time you walk in that room (unless the pattern changes). Same goes for Daphne's eyes. There is no point in fixating on it, unless you plan on comparing the shade of blue to something else, eg; "..her normally bright, azure eyes looked dull and lifeless.."
Paint the scene by all means, but paint different parts as you do. Eg, how about the pattern on her shirt? Barefoot or slippers? The jacket or robes Christopher is wearing, the wood used for the dining room table, etc..