I am confused about how the specific magic weapon Shatterspike is worded.
This intimidating weapon appears to be a longsword with multiple hooks, barbs, and serrations along the blade, excellent for catching and sundering a foe’s weapon. Wielders without the Improved Sunder feat use a shatterspike as a +1 longsword only. Wielders with the Improved Sunder feat instead use shatterspike as a +4 longsword when attempting to sunder an opponent’s weapon. Shatterspike can damage weapons with an enhancement bonus of +4 or lower.
Its the last line "Shatterspike can damage weapons with an enhancement bonus of +4 or lower" that has me confused. I know in the original pathfinder rules that a +1 weapon was unable to damage weapons or armor with a higher enhancement bonus, but that was changed at some point to enhancement bonuses increase hit-points and hardness. In any case, the wording here doesn't make sense to me. Under either rules a +4 weapon would be able to damage other +4 or lower weapons, so why call it out?