A friend of mine has a pretty good Arakune. He likes to grab like an ass though. Literally. If all Arakunes are like that, you can keep using the 236C or B to flinch him, then run in for some damage. You really just have to keep your distance. Keep in mind that you can shoot those little rodents that curse you.
And Arakunes like to fly, a lot. So try to catch them in the 6C then unleash hell.