Ignoring argument...
So what freaks Tokiomi out the most here, the instinctive understanding that he is looking at a Messiah, the insta healing, or the idea that Minato basically pulled true magic or close to it with jewelcraft? (From a Likely Magus perspective)
Oh what I meant with not needing to master the second to travel between worlds is that just moving yourself between worlds is not all of the second, in the same way that Tsubame Gaeshi is not all of second magic. Someone with sufficient effort (Truly ludicrous amounts) could gain a piece of true magic, just not all of it, that would require Zel to die.