Couple of years of Wing Chun. 4 years of Haganah (close relative of Krav Maga). Really enjoyed the knife fighting part of Haganah. Learned enough about knife fighting that if someone pulled a knife, your best bet was to have a firearm. Knife disarm tactics are even more problematic. Luck and a lot of skill is needed to avoid getting cut or stabbed. Back in the day when I was moved to the training section (retired Fed) did quite a bit of ground fighting with other Defensive / Control tactics instructors.