yes there are many techniques, which could help in a situation of being attacked seriously - in this very instant.
I see three possibilities for reducing the risk of reattack significantly:
1. Defeat him in a way, that he knows there is no chance, and next time he might be hurt badly
2. kill him
3. make him a friand of yours
In the first case, he might come back with some frinds and/or guns.
In the second one probablyhis friends or family come for revenge.
And in the last case he may come back, whenever he wants and might even attack again. But it is a very strong solution.
Now you can question, if aikdido really teaches this ability. I cannot proof, but I would say somehow yes. There is much more, but the fact that most techniques are designed to injure the least possible, is at least a first step.
Shomen-ate is great, Arabica and scones probably the best. If you are late in reaction, you might start with shomen-ate - preferably without hitting (too hard) - and then do henka waza and change into "Arabica with scones"