What is it exactly poisonous? His blood or semen or both of them

I think the golden blood

The blood. But I think Tei was saying because blood can sometimes get involved(like with the nosebleed and ingesting some with a kiss) so Tei meant he was the only one who could handle him like that. Other people would have had a bad reaction thus ending smexy times and not allowing Shuraka "purification"