For a single handed weapon, is the 42" just the lengtrh of the blade or the total length of the weapon?
Total length of the weapon hilt to tip usually.
All lengths are total length of the weapon. This is for several reasons, but mostly because larp weapons are so light, it’s otherwise quite easy to get nearly arbitrary reach by having a very long handle and holding near the pommel. Also it’s easier to measure, and has less arguments about what counts as parts of the blade instead of the guard, etc.
I have an 18" blade on a 5’ pole… This is not a dagger.