Well, it's still not a pure blood even if it's disguised as say, Jaki. Because you can't really copy her ability of being fucking poisonous. So, copying the ability of her blood would also be out of the question.

Also, I think the wards should be those cute lil lion statues. Let's put some in front of the gate and they can move but never leave. Cuz that'd be adorable and their purpose is to protect homes from evil spirits, so they'd make great wards.