Board Thread:League of Legends discussion/@comment-24890581-20140501235148/@comment-24792363-20140710183632

visage doesn't necessarily refer to the semblance of a face, that's just its most common associative meaning

visage can also refer to the general aspect or appearance

so as it's a chest piece in the icon, I would assume that SV would allude more towards its wearer becoming more incorporeal, or maybe it resembles the visage of a spirit.