Circular Saw 7 1/4 is great. But when you have to cut an example a piece rotten wood off a rafter. The saw is too heavy and awkward standing on a ladder. Is there a smaller circular saw you can use on a ladder

Sawsall.

HD And Lowe's carry battery operated saws. Pricey and not sure of battery life

Hi,
Reciprocating saws are popular for this task as well since they allow for a different way to hold them when in use.
Peace,
Clarke