Dragonkin and reach weapons question

[Banecrow]

So a dragonkin has a reach of 10 feet normally. If they are using a dragonglaive which has the reach special property does this mean they now threaten squares up to 15 feet away?

[Owen K. C. Stephens]

Yes, as detailed in "Reach and Threatened Squares" on page 255 of the Core Rulebook. (Fourth paragraph under that heading, last sentence).