OK, I'll start with gym question. When someone is helping you lift weights they are called a 'spot'. 'Can you spot me while I lift these weights?' So, if the spot is a little kid, then he would be a weak spot. And not much help if you're lifting a lot.
For the stain question, if only water is sufficient to remove a stain, then it wouldn't be much of a stain, like a grass stain on your pants. Say you spilled some soda on your shirt, which would make a spot, then you put your shirt under a running faucet to remove the spot. That's a pretty weak spot because you didn't need soap or something abrasive to remove it.
For the Siren one:
Come to me and I bring death
come to the mythical siren and thy will try to (and usually, except for Odysseus) kill you
Await me and I bring life
You wait for an ambulance siren or any life support siren. Just stay where are; don't move and make your injury worse. And you will hear the siren coming closer and closer bringing you (hopefully) the means to keep your life.