I really appreciate that you pointed that out. Why do I miss the best details?
Actually, I think that's the joke - while Tenryuu and Kiso think their eyepatches make them look cool, their respective sister ships think they'd look cuter without them.
Really now, if Tenryuu-chan didn't have that about her...If Kiso didn't have that either, she'd be so cute-kuma.Oh my, Tenryuu-chan's the cuter one, you know?Hmpf.My, oh myyy!Kumakumaaa!