I Solemnly Swear That I Am Up To No Good

I've been thinking about those self-defence practices we've been doing and I had two thoughts.

One is, I was practicing a lengthening charm for clothes and I was thinking about all the charms that could be used as jinxes, either by themselves or in combination with something else and how this could be a brilliant way to take someone by surprise. For instance, a lengthening charm from one person and an entangling jinx from another could get someone all tangled in their robes. There's a charm that's supposed to make you more relaxed, if you're all tense, and it's actually very pleasant but if someone cast expelliarmus on you at the same time it might not just take your wand but completely knock you over. There's probably even a way to use a cheering charm offensively. (Well, maybe the cheering charm would just put the other person in such a good mood they wouldn't want to hex you anymore anyway? that wouldn't be so bad.)

The other thing I was wondering is whether it would make sense to work out some hand signals for some of the combinations we've practised. Like, three fingers in the air mean, 'I'm going to cast the jelly-legs jinx, you cast expelliarmus,' or whatever. Only I'm not sure if it would be any use, because I don't know if I'd remember them in the middle of a fight plus once I'm in a fight I'm going to be looking at my opponent to see where they're aiming hexes, not at my allies so much. But it might be worth trying. What do other people think?