Top-handle saw
A compact chainsaw whose rear handle sits on top of the machine rather than behind it, allowing controlled one-handed operation. It is designed for arborists working aloft in a tree on rope and harness.
Top-handle saws exist for a narrow professional purpose and are dangerous in general use: the balance that makes them manageable from a climbing line also puts the bar much closer to the operator's body, and one-handed use removes the grip that resists kickback. In several jurisdictions they are legally restricted to trained and certificated arborists. For ground work, pruning included, a small rear-handle saw does the same job with far greater control. If you do use one, a chain brake, a saw lanyard and cut-resistant gloves are minimum equipment.