ive only used old waterski gloves and a knife in the 0 visibilty lake i do the work in... ive had to cut myself out of fishing lines and loose ropes, and the gloves keep me from cutting my hands on things i cant see. i dont see why you'd need gloves or a knife in clear waters.
I do agree, instructors need to do a better job of teaching buoyancy. I did my part a few weeks ago on the aggressor where I got one diver to go from 12# to 6#, dropping 2# per dive until he got the least possible weight. I got another [new to diving] diver to drop 4# as well. They were surprised when i showed them you can dive with zero weights, which I did the last dive.