Heshikiri Hasebe's original owner was Oda Nobunaga. Shokudaikiri Mitsutada was once owned by Oda Nobunaga before being handed off to Date Masamune.
Taikogane Sadamune is a tantou made by the sword smith Sadamune and also owned by Date Masamune. It appears Mitsutada may be hinting at the addition of this sword in the future.