I have to agree,I always 'ping'the blade.It seems like INFI makes an almost brittle sound like it would snap at the slightest bend,of course we all know better.But each blade does have it's own sound.I was reading a Lone Wolf and Cub comic(I know it's a comic book but bear with me)Anyway the main character Ogami Broke an enemies sword with his own Katana,he knew it would break because of the ring of the steel when they locked blades,this resulted in the enemies death.I know this is just fiction but anyone familiar with this series knows the amount of great historical detail that goes into them.No magical swords or half cat people,just very realisitic representation of the time period.Anyway I always think of that issue whenever I hear the different sounds of blade steel 'pinging'