it's all relative, as in the theory of relative where you should never lend them money. if you notice, many aikido weapon works, folks don't really want to nail the other person, so they pull way back and not much intent going out. it's a difficult balance when you practice not to pull your strike, but still have precision of control and not doing slow-mo matrix style.
btw, blocking shinai with your head is an acceptable form of entertainment, for other folks watching.
Itīs true abut holding back your intention