I found Bashiok today and I tried to hit him with the rakanishu sword, but nothing happened.
Tried both with basic attack and skill, but nothing happened. Then tried inviting a friend, but still no result... As a last chance, I tried to buy many rakanishu sword in the auction house and used them all to hit Bashiok. Nothing.
Could you solve this and tell us how to complete the achievement?
Thank you in advance.