Since it started out as models, Warhammer 40k is all about looking as dramatic, badass, sexy etc as possible. Hell, most of the time even the characters themselves can't make any sense of the setting. That's part of what Space Opera is all about.
When in doubt, remember Orky tech: - If it looks good, it IS good. - Bigger is better. Always. - If it lacks firepower, put another gun on it. - If you have more stuff, you are better. Period. - If you paint something red, it goes faster. - "Looking cool" and "working well" aren't just happy coincidences, they're mutually inclusive concepts.
If we must be practical, that "I" she has is probably a ver small Rosarius, an over-shield projector. She's weilding force-weaponry, so she's a psyker, and she's probably got a dozen witchy tricks up her sleeve.
I mean, these people have an Artillery battery that looks like a Church Pipe Organ.
Not to mention the Imperiums general design concept of covering almost every square inch of any vehicle, building or suit with random skulls and purity seals. Also shoulderpads. Gigantic shoulderpads are always a good idea.
