Originally posted by: Mut@t@
for rasengan, the version i have says this:

"to appreciate the degree of difficulty of this jutsu, he (4th) was six grades above the second... 'a'-rank ultra-high grade level"

"in order to comprehend the jutsu, you need to be at 3rd grade level jutsu"

i don't know what version i have but those two sentences make zero sense to me...
i think,
rasengan lvls
1=water balloon
2=rubber ball
3=control.
"in order to comprehend the jutsu, you need to be at 3rd grade level jutsu"
so after lvl 3 u can use it
4=??
5=??
6=??
maybe we get to see other training of jiraiya later on.
and for measuring
2+6=8= 4th's lvl of this jutsu ( get a understanding how great the 4th was, of course it'd make no sense why say 6 grades above the second )
or he means yondaime was like god compaired to the second hokage

^all speculation >_>