Opportunity Attack Range

[moshner]

It makes no sense to only threaten when someone leaves your threatened area. Bring back the rule 'moves through your threatened area" from 3.5e.

3.5e:

You threaten all squares into which you can make a melee attack, even when it is not your action. Generally, that means everything in all squares adjacent to your space (including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you. If you’re unarmed, you don’t normally threaten any squares and thus can’t make attacks of opportunity.

Reach Weapons Most creatures of Medium or smaller size have a reach of only 5 feet. This means that they can make melee attacks only against creatures up to 5 feet (1 square) away. However, Small and Medium creatures wielding reach weapons threaten more squares than a typical creature. In addition, most creatures larger than Medium have a natural reach of 10 feet or more.

Note: Small and Medium creatures wielding reach weapons threaten all squares 10 feet (2 squares) away, even diagonally. (This is an exception to the rule that 2 squares of diagonal distance is measured as 15 feet.)

[moshner]

We need to see how this plays out for a bit longer