Each system has a concept of a true guard. Not true as in the opposite of false but true as in loyal, trusted and true Or straight and true.

They are almost default guards - don't know what you're doing or facing. This will skew the odds in your favour.

Best to illustrate with Iron Door from Fiore.

This is a low wide guard, starting at bottom right and the defence is stepping slightly offline while bringing the sword up to window (pointing in your opponent's face) This cuts through all lines of attack and ends with a credible threat.

Silver's True Guard is a hanging guard, hand over forehead, blade towards knee. Defence is unwind and step offline