Normally the golden rule of blocking in fighting games
w̶i̶t̶h̶o̶u̶t̶ ̶b̶l̶o̶c̶k̶ ̶b̶u̶t̶t̶o̶n̶s̶ is that whatever direction your opponent is relative to you, hold the opposite direction to block their attacks. If they get to the other side of you, then you just block the other way.
This is not the case in Art of Fighting 2. Should you get knocked down and your opponent jumps to the other side, it takes a frame or two when you get up to turn around. If they connect with an attack during that time, you still need to block whichever direction was “backwards” when you got knocked down, regardless of which direction the attack is coming from.
Here, Ryo is attempting to block this sweep by holding down-back relative to his opponent. Doesn’t work.
Here, he successfully blocks it by holding what is supposed to be down+forward, but is actually just the same down+back from when he got knocked down.