To some extent, all weapons are a case-by-case thing. Every weapon has to fit within the guidelines laid out in the rulebook. Every item is classified into a group and must fit the specifications of that group. If the linked items were a little longer and were approved on-site, they'd be daggers because most of the melee classifications are entirely length dependent.
Evan is correct, you can't bend kitespar, but you can bend pvc relatively easily. Some players still use PVC weapons, and for shorter weapons there isn't much difference. That said, we generally don't allow joints in weapons, with the notable exception of bows because they're blocking only.
On a related note, while curved weapons are entirely legal, there's a good reason that most people don't use them. They tend to be fairly ineffective and tricky to fight with well. You can, of course, play with whatever weapons fit your character, but you may want to consider playing with some bent weapons for a few games before spending a lot of money on latex versions.