This is a completely different system than what was mentioned earlier in the thread about Kings being cardinal signs (Cancer for King of Cups). The confusion here is that both systems call themselves ‘traditional’ but they’re actually incompatible with each other. WIth the system you’re describing, Kings take the mutable portion of their element, which would make King of Cups purely Pisces (mutable water). That’s cleaner elementally than the Golden Dawn’s degree ranges that span two signs.
The earlier poster assigned King of Cups to Cancer (cardinal water) based on a rank-to-modality system where Kings=cardinal, Queens=fixed, Knights=mutable. Your system does the opposite for Kings and Knights.
Both systems have internal logic, but readers need to know which one they’re actually following. Tarot books often don’t specify which attribution system they’re using, so beginners get totally mixed messages about these correspondences.