Work that runs along a line rather than sitting at a point: clearing solder bridges across rows of pins, soldering and desoldering connector tags and terminal blocks, dressing excess solder off an edge, and heating several adjacent leads together. The straight edge is what distinguishes it from both pointed and flat-faced geometries.

The edge is drawn along the shorted row in contact with the pins, trailing slightly, so the excess solder melts and is carried away on the blade while the individual joints stay intact. Added liquid flux helps considerably. A pointed tip tends to redistribute a bridge rather than lift it, because there is nowhere for the solder to collect.

A bevel or hoof is the better tool where the aim is to deposit solder along a row, since the angled or cupped face carries a reservoir. A knife excels at the opposite task - removing excess and separating joints that have run together. Many rework benches keep both and switch between them during the same repair.

Yes. Although it looks fine, the contact is a line rather than a dot, so it delivers substantially more heat than its appearance suggests. Laying the edge along a connector tag, a terminal or several through-hole leads brings them up together, which is exactly what is needed when desoldering a multi-pin part.

As close to flat against the joint as access allows, so the whole edge contacts and transfers heat along its length. Presenting it steeply reduces the contact to the corner of the blade and forfeits the advantage. The edge is a heating surface, not a cutting one - prying or scraping with it breaks the plating and ends the tip's useful life.