Annkles crossed would be a scissor. How do you tell if it is punishing. That one is a little more difficult to answer. That is left up to the judgement of the official on that mat. Some things you typically look for would be: audible or verbal clues from the opponent being held in the hold, visual clues such as skin color (as funny as that seems), and very importantly, if the wrestler having the hold applied to them can be pinned in the situation. In other words if a wrestler has a scissors applied and the opponent really cannot be put in a position to get their pinning area on the mat, this would be a situation where you would be looking for punishment. It doesn't make sense to scissor your opponent and squeeze them when their body is physically incapable of moving into a position of being pinned.

Often times its easier for an official to audible tell the offensive wrestler something to the effect of "Don't use that for punishment, or keep it legal" Wrestlers should know the rules, but if their coach never told them, or coached them in defiance of the rules, an official needs to have discretion.

Ultimately it does come down to judgement in this situation though.