Well, the crafting bonus is, as Sanctaphrax already said, going to be a problem. It is at least an 8 shift block, but I would calculate with a 10 shift block to be on the safe side.
To get him in 1 exchange, you will have to hit all his consequences (20] + his block (10) + physical stress track (3) +1 to make him fall over = 34 shifts of damage. If you go all out, you can get 14 of that by taking massive amounts of casting stress (2+2+4+6). 4 conviction gives us a 17 shift spell, which must be controlled by another 17 shifts on a discipline roll, and we are precisely at 34 shifts. Now lets take a worst case scenario of a -4 roll, which will get you down to +4 with foci and lawbreaker (this is calculated for water, since it is your best element). That would mean, you'd need at least 7 aspects to tag or fate points to invoke to kill him with one enormous blast of however you employ your water magic. Not taking into account, that he might be able to spend fate points of his own, in which case you will be absolutely screwed using this tactic.
The way I'd try to do it would be to shut him down first. Get some of his hair or other symbolic links. It will make it significantly easier to shut down his magic. Like I said before, with that many "ice" aspects, he is probably going to attack mainly (if not entirely) with ice attacks. If you lock down the entropy in the arena, he will no longer be able to shift around any heat, and since cold is the absence of heat, he will not be able to form any ice spells to throw against you. Even magic has to oblige physics at some point. After that, he can flail his arms, but he is pretty much dead in the water (pun intended).
If you have enough time before going into the duel, you could try to make a potion that will let you reflect his attacks. Since the item is specifically designed to reflect his spells at a specific location, you can get all kind of aspects to improve the potions power (dirt from the arena, hair from your opponent, a piece of something that has been hurt or destroyed by his magic, a snowflake for the element he uses, and so on). I use potion here as the catch-all word for one-use magic items, it can be a voodoo doll, a wristband, a carved stick, a scroll, pretty much anything. If you are able to sneak it in, better for you.
If you can go first, either stall and let him throw the first punch (to reflect his spell and then use your action to finish him), or use it to maneuver, just in case.
