I'll take my kunai. Fuma still gets used plenty due to the gcd clipping that has been pointed out. I only use Raiton if Kassatsu is up outside burst windows. Those who can weave it without clipping are far better NIN than I... or have godly ping^^

Fuma also has greater range than Raiton if mechanics force you even outside Raiton's range, and you'll also want to go Fuma if the boss has some kind of magic mitigation up.