Calamacil are one of the better injection moulded brands. But all injection molded LARP weapons suffer from the same issues: they lack consistency, often the foam is too hard (though it usually softens in use), the core can be misaligned within the mould meaning it’s too near the surface, and once they start to degrade (as yours has) it is very hard to repair them as they are made in one piece.
Whereas with the core and layered foam weapons, the maker has much more control over the density of the foam and where it’s applied, and if one area of latex and/or foam wears out it can often be stripped out and replaced without having to repair the rest.
Calimacil are fine if that’s what you like. But as a general rule you will get a sturdier and better-lasting weapon with core and layers construction.