Quit now. Constantine had nothing to do with Christian Eucharistic theology. He did legalize Christianity and gave public buildings to Christians as houses of worship, and to his credit he attempted to defend the Christians of Armenia from conquest by the Persians, but he did not live in the Faith nor even call himself a Christian. Finally on his death-bed he chose the Arian bishop Eusebius of Nicomedia, not a Catholic, as his baptizer.
I know our esteemed friends the Orthodox have a different view of this, but in the Catholic Church he is not seen even as a fellow believer, let alone a canonized saint.
And what dd he have to do with the Eucharist? Ningun cosa. Nada. Zilch. He had nothing to do with Catholic theology.
You're evidently a victim of spurious history purveyed by people who don't know jack chick about Catholicism.
Sound like a VERY big 'something' to me!