i've been looking at some of the swamp rat and scrap yard knives to buy. but i was wondering why most of the knives i was interested in, didnt have a complete blade. almost all of them had a semi circle cut out at the base of the cutting edge, right above the handle. it is my understanding that this is for a finger when doing more delicate cutting. what is this called, and does it have any negative side effects on the knife's abilities or limitations? thanks alot ahead of time