That being punched thing is really not comparable to being hit as hard as Link was, even with the flat of the axe, Link was unhurt and the boar sent flying. That's a lot of force, and it's not like it's Link's only durability feat.
I posted a video earlier of him stopping a 60 ton-ish rolling Goron without being crushed, for example.
Both of those produce enough force to damage steel. 😛
Another thing that occurs in Twilight Princess is that Link is fired out of a cannon in the sky down into lake Hylia. Sky cannons are powerful enough in TP to send Link to the city in the sky.
I never have been able to find a video of that though.