Zeus the grapple wasn't unbalanced in itself. It was just too fast for the rest of the game based on the q2wf mod which had a slower grapple. This difference created the unbalance.
The other mod you're talking about is LRCTF and I happen to be in the devteam of this mod too. They basically took the code from alliance (the founding members of the lrctf devteam were part of alliance's one) and thus it's grapple.
Alliance isn't a good example btw cause it died more than one year before wfa.
Finally thx to OD & Niall, about 3lvl2 you indeed should give the props to slacker, he's the one behind the fun. I just gave the map a facelift :)