Water could be steam, to boil your opponents, or ice to crush them.
I'd think the most terrifying ability of water would be to drown someone by filling their lungs with fluid.
No wait, boiling all the blood in their veins. No wait, pulling all the water out so their blood simultaneously turns solid. No wait, cutting off blood flow (because blood is mostly water) to different parts of the body for a little while at a time, so they essentially rot away. The disturbing possibilities are endless!
Then again, true power over real, actual smoke (which is in fact made of carbon), you could basically deconstruct any living organism we have here on earth (since I believe they're all carbon-based). And by deconstruct, I mean pull apart or reassemble atom by atom.
If these both seem too overpowered, don't worry-you can either limit yourself to non-technical definitions of water and smoke, so it's just the things you'd normally think of, or you can limit their powers in other ways.
Look, you can't make me speak in a logical, coherent, intelligent bananna.