I have had my carry-on weighed at airports in Europe (flight to Egypt) and Asia. I believe some Caribbean puddle-jumper airlines weigh carry-on bags as well. When booking international flights, I always look out for carry-on weight limits. A common question on travel forums is how strictly such-and-such airline enforces their own stated limits.
Also, with regard to lead weights, this may be one of those items over which security personnel (e.g., TSA in the US) have some discretion, as there are rules out there prohibiting items that could be swung as a weapon (I believe "cudgel" is a term that is sometimes used). Baseball bats are clearly prohibited. But it occurs to me that a brick might be suspect. A lead dive weight? The vast majority of TSA agents may not bat an eye, but don't be surprised if it gets flagged someday somewhere.
Also, with regard to lead weights, this may be one of those items over which security personnel (e.g., TSA in the US) have some discretion, as there are rules out there prohibiting items that could be swung as a weapon (I believe "cudgel" is a term that is sometimes used). Baseball bats are clearly prohibited. But it occurs to me that a brick might be suspect. A lead dive weight? The vast majority of TSA agents may not bat an eye, but don't be surprised if it gets flagged someday somewhere.