when is a hand off considered illegal?

[ccc19]

I had a sevens tournament the other day and in one of the games I got penalized for doing a hand off.

For me it just seemed like a regular hand off, I did not clench my fist or anything however there was definitely a lot of force behind it.

When is a hand off considered illegal or dangerous, so that it can be penalised?

 

[Cruz_del_Sur]

Well, if it is near the eye or the eye area (whatever the **** that means) it could even go as far as being a red card.
I'd say face is a grey area at best. Rule book gives the ref enough tools to punish you if he wants to. Open hand, top of head should be ok in mist situations.