...and blading. Before you knew what you were looking for. For me there was a time when I did not know about the blade (that changed in the early-mid 80's..The Stossel piece might have actually been what clued me in...memory is fleeting on knowing about it before that bit).
Once you look for it, it is mostly obvious when it is put in use...but before that, when a guy would come up bloody, it grabbed your attention immediately.
And AFTER you knew about it, and you missed it happening, it was still an "oh wow, I missed that!" moment.