Did St Nicholas really slap Arius?

Well if the truth be known, St Nicholas never slapped Arius.

There are some problems with the story, though. In the first place, it’s not true. The story has no historical value. As the old Catholic Encyclopedia notes, it’s doubtful St. Nicholas was even at Nicea, since the historical lists of bishops that attended that council don’t include him. Instead, Nicholas is linked to the Council by much later hagiographical works written over half a millennium after Nicholas died. Let’s Stop Celebrating St. Nicholas Punching Arius

Here is the excerpt of what the old Catholic Encyclopedia has to say about St Nicholas:

There is reason to doubt his presence at Nicaea, since his name is not mentioned in any of the old lists of bishops that attended this council. - Catholic Encyclopedia

But how did this legend come about:

According to Roger Pearse, editor of the Tertullian Project, the account of the violent incident at Nicea apparently shows up first over a thousand years after the Council, in a 14th-century work. Even then, it isn’t Arius himself that Nicholas supposedly struck, but only “a certain Arian.” That story wasn’t good enough, though, so a couple of centuries later another writer changed it to Arius himself. Note, too, that the medieval accounts have Nicholas slapping — not punching — the heretic. The story describes a medicinal slap or a rebuke, an attempt to “slap him back to his senses” rather than an expression of contempt or a wish to harm, as a punch certainly would be. As such, the moment is celebrated in Greek iconography. When I say “Let’s stop celebrating St. Nicholas punching Arius,” I don’t mean to demean this tradition in Greek iconography. Be that as it may, in the original story the blow is not celebrated as a high point of the Council. On the contrary, for striking the Arian heretic, Nicholas was reportedly deprived of his mitre and pallium. The later story, which changes the heretic to Arius, also ramps up Nicholas’s punishment, having him thrown into jail — and has him vindicated by no less than Our Lord and Our Lady, who appear to Nicholas in prison and, hearing that his has been imprisoned “for loving You,” free him of his fetters and clothe him in an archpriestly vestment, to the astonishment of those who come for him in the morning.

All said and pondered over there is no historical evidence that St Nicholas punched Arius.