Reach Weapons and Large Creatures

[tivadar27]

Ok, so I'm wondering if the template for reach weapons is somewhat off for large creatures (or rather, maybe just misleading).

First, I understand large creatures natural reach allows them to hit the 15 feet diagonal, even though that is in fact 15 feet away and not 10 feet.

Second, from what I've read, reach weapons "break" natural reach rules, and more specifically: "A typical Large character wielding a reach weapon of the appropriate size can attack a creature 15 or 20 feet away, but not adjacent creatures or creatures up to 10 feet away."

The grid painted online lists the second diagonal as within the creatures natural reach, which is correct, but that should also be within the creatures reach with a reach weapon as well, correct?

[Komoda]

The rules are broken. I believe current RAW states that the 15' corners are not threatened by 10' natural reach. Therefore should be threatened by a reach weapon of a large creature as it falls with the 15' to 20' mark.