Of course it has limits. Otherwise it'd be a no-limits fallacy. Except that limit is Sidious, who is better than Krayt in everything. Krayt has never summoned Lightning even approaching the potency of Palpatine's, which was literally bending Mace's saber in the RotS novel. Whereas in Legacy: War, Krayt's bursts of Lightning was repelled just fine on Cade's lightsaber.