Deburring Design
Deburring tools' tips employ a clever design. The deburring shank has a jog in it. The shank swivels in the handle. The swifel action orients its blade appropriately along any edge you drag the beburring tool along. It's not unlike a child dragging a stick behind him when he walks; the stick naturally follows. Only, with a deburring tool, the stick has the added purpose of removing a very fine edge as it's dragged along.
Thin Handles
Most deburring tools' handles don't diverge much from a pencil's design. While a pencil is a perfectly serviceable design to write with, it's not a good design for a tool you wield with your hand, wrist and arms instead of just your fingers. These thin handles are made to be plucked from a workbench, run across a couple edges, and then put back within a couple of minutes. If that's all you use it for, a thin handle is fine. But if you need to use it longer, you might run into problems from an ergonomic standpoint.
Thicker Hangles
Pick any handled tool you'd expect to use for a hour or more. Most feature plumper handles to to fit easily into the palm of your hand. The larger handle suits the less nimble dexterity of wrists and relieves unnecessary finger strain. This is the kind of grip you want in a deburring tool you'll use frequently.
Formed Handles
Another way to choose ergonomically appropriate deburring handle is to think of all the hand tools you use that have a unique shape. Consider screwdrivers with ridges along the handle shaft that give you leverage, but not necessarily comfort. Pairing knives feature thumb indentations for the end of your stroke. You're likely to imagine all the ergonomic features you want when you picture the handles you regularly use. Keep these images in mind when you shop for your deburring tool and you'll find one that's suited for more than five minutes' use.