It was only an attack designed to kill Tristan, though. It doesn't seem like Arthur put any effort into it.
Speaking of which,
2nd Mark (at least 329.76 Teratons) > Base Meliodas (even without his mark,
they could fight, and Arthur had to
avoid a slash and
parry his other attacks) > Arthur's Full Countered attack (at least 82.44 Teratons) > Arthur's attack > Post-Meland Demon Tristan > Pre-Meland Demon Tristan > Enchanter Tristan (at least 41.22 Teratons) > Tristan > Chaos Melascula's Cocoon > Melascula's Cocoon > 2nd Mark Post-Revival Demon Meli (20.61 Teratons)
Depends on various factors, like distance.