I find this to be decent case for my extra-long Tanto from Seido and I can tell that it would comfortably fit other, smaller Tanto and something slightly longer too (though not much!).
This case does its' job, in that it conceals the weapon and would render it harmless if someone tried to take it from you, however I would not feel completely sure that it would protect the wood inside if it was dropped or thrown.
Whilst this is Ideal for holding a single Tanto I would certainly not purchase a bag made of similar material or style for larger weapons.