Specific magic weapon Shatterspike confusion

Question

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?

Answer 1

Rules are often repeated when relevant, particularly obscure ones like this. In all likelihood, it was solely meant as a reminder of this rule when it existed, and possibly to prevent anyone from arguing that “using” it “as a +4” didn’t mean it was a +4 and so it still couldn’t damage those weapons.¹

As it was probably just reminder text/confirmation that shatterspike really works like a +4 when sundering, yes even that way, we should probably not read anything more into it than that, and update shatterspike along with the rest of the rules about sundering magic weapons.

1. _{One might wonder how you use a weapon “as a” +anything in that case, though, since the use of such weapons is identical to those with lesser magic, and indeed to non-magical weapons. But I never said it would be a good argument, only that people might make it. Cutting such things off at the pass is often necessary in rules-writing.}