I've never used the @$blah variable type before, and I couldn't find any information about it. I'm guessing that's how you refer to the arrays in an array of arrays?

Yes, that is one way to do it, known as dereferenceing because $blah is a reference, see references quick reference

Its nice you picked up a new trick, but I would still use sort :)

$ cat fafafile
3       6       1
1       2       0
9       1       9
4       4       5
7       3       2
0       5       4
6       7       6
2       9       8

$ sort --dictionary-order  fafafile
0       5       4
1       2       0
2       9       8
3       6       1
4       4       5
6       7       6
7       3       2
9       1       9

$ sort --dictionary-order --key=2,2 fafafile
9       1       9
1       2       0
7       3       2
4       4       5
0       5       4
3       6       1
6       7       6
2       9       8