The typical Opinel knife which is cheap, handy and reliable does sorta rely on "locking", but it's a manual process. They can be opened with one hand, but it's

The typical Opinel knife which is cheap, handy and reliable does sorta rely on "locking", but it's a manual process. They can be opened with one hand, but it's slow and nothing you could do while using the same hand to fight. They have to fit the wielder's hand, however... big hands tend to require too large knives... I'll have to agree however that the blade is brittle. You can't stab something that moves with them, unless you want it to break off.