Robust
A samurai who can fight with icicles on him is more robust than regular samurai. Can you imagine how robust you'd have to be to fight in weather cold enough to form icicles on your body?
Picture samurai standing in a line. One, two, three... woah. You look up. This guy has icicles growing off him and he's the size of a bus. Now that's a robust samurai.
そう
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You may think it's just his robust body, but it's actually the samurai's robust soul (そう) that keeps him fighting through the cold and the icicles.
Physical robustness is just a reflection of the strength of your soul!