The one in the MM2 is quite different from the old-school Water Weird. First, there are now four elemental weirds, and second, they are now oracles you come consulting, rather than enemies you stumble upon.
Yeah... personally, if someone converted the 2E water weird (or its cousin from MCA1, the earth weird), I'd recommend giving them a different name to distinguish them from the ones in 3E MM2. Like, 'lesser elemental weirds' or something like that.
Got that one from uh....Lance Hawvermale or Patrick Lawringer (dont remember which one). One of them stuck the water weird in a Necromancer Games book and renamed it the Drench.
But- I agree with the above. the 3e water weird found in MM2 is NOT the original weird by any means. It is totally different. Nothing wrong with a hot chick made of water (or air or fire or whatever)...its just not the original weird though.