I think most gestures are self-explanatory. You show the palms of your hands to mean you have nothing to hide, thus “I don’t know”. You bow to show respect, because you are symbolically showing you are “lower” than the person you give respect to. Etc. But one thing has always perplexed me: how did “whittling” your index fingers come to mean “shame on you!”. I mean, what symbolically are you doing when you do this? Also, how did making your hand into a “bull” symbol come to mean “I love you”? Bull=“I love you”? That’s not what I take that symbol to mean, at face value at least .
I think, that the “whittling” gesture you refer to is meant to be “scraping” shame off on the person. IIRC, I believe it’s said that the “bull” gesture is a form of compressed/combined “I Love You” in sign language.
The I love you hand sign is supposedly a real ASL sign. I say ‘supposedly’ because I’m too lazy to cite and don’t want to assume wrongly.
The Horned Hand (see bottom of page) or “Bull’s Horns” or “Metal Symbol” is different.