If ever a sword were going to hit on the correct vectors to make it relevant in vintage this might be it.

Protection protect is from Jace bounce, Swords, being blocked by Mentor and tokens, Delvers, Snapcasters, etc

+2+2 likely puts it out of bolt range (you probably tutored this with stoneforge right)

Ability makes it an unavoidable clock and makes your walkers get bigger.

Probably won't see play but I wonder if we get a whole cycle now?

Sword are just too slow for Vintage imo. I don't think this is better than Sword of Fire and Ice. Protection from Mentor is cool, but if you're trying to race Mentor with this you are going to lose that race.

It let's you keep the new Narset around longer. Swing, grow, impulse every turn is not bad.

Equipment aren't really that slow. It's more the lack of Brainstorms making Stoneforge Mystic comparatively much worse, artifact removal rampant because of Shops, oh, and Mr. Dack Fayden. @Serracollector is right. This seems like a plan to work with the current planeswalkers. I think it's better than people think, but more intended for the casual crowd.