Sand

In uncertain scenarios, a handful of sand, salt, earth, dust, and so on, will do wonders. Just that alone will give you an easy opportunity to overpower someone.

Just throw it at their face and your opportunity will present itself. If they close their eyes, then they basically blinded themselves. If they keep them open, they'll be blinded. If they try to avoid it, they'll have to take their attention off of you momentarily.