You bought a saya to keep your knife safe. Smart move! Just remember to dry your blade thoroughly before slipping it inside. Trapped moisture can lead to rust, and that's the last thing you want for your favorite knife.
A saya is the ultimate bodyguard for your edge, preventing chips and dings when your knife is not in use. But if the blade is not properly dried before it's stored, the saya can trap moisture and the blade could eventually start to rust. Here is the strict protocol: wash the blade, wipe it down thoroughly, and let it air dry for a bit before putting it to bed. The saya will do its job flawlessly, but only if you do yours.
Moisture needs a way out. A tight-fitting saya helps shield the edge from bumps, but it also creates an enclosed space. If either the blade or the inside of the sheath is damp, that trapped moisture can encourage corrosion over time.
Before storage, wash and dry the knife completely, paying attention to the area near the handle. Check that the saya itself is clean and dry too. For longer storage, consider an appropriate protective oil for reactive carbon-steel blades and keep the knife somewhere dry.