If you take a look at the mission 60 deck, you'll notice that not a single one of the cards has Siege: http://warmetal.wikia.com/wiki/Mission_60_%28Deck%29
That means you can take advantage by having some structures in your deck. If you're going to use Hatchet (which is a great card), it helps to back it up with an Asylum.
Also, notice that 7/9 Assault cards have flying, but you only have one card with anti-air, four cards that fly; I would recommend making a few changes there.
Another thing: the entire deck is Xeno, so you can take advantage of that by using structure cards that target Xeno for maximum effect. A perfect example of that would be Comsat Terminal, which weakens all Xeno by 2 while rallying all imperial by 2.
If you have Electromagnetic Pulse, you should be packing it along for the ride. There are two cards that have <=2 health, and four cards that have 3 health. If Sabre is out, and you use your EMP, that could wipe a lot of their cards off of the table. Remember to hold off on EMP until a little bit later in the fight if you can, since it does more damage that way. That isn't always good advice, but as a general rule, it works. Just look for the right time, when you'll destroy the most cards in one complete turn.
What other commanders and structures do you have? I love Arc Soldier, but he misses a lot in this fight. That card with pierce and leech could probably be switched out as well. I recommend you throw jet trooper in there--it only has 2 health, but it flies, does 3 damage and you could probably use the extra heals. Another killer card would be Fighter Jet, which you can get by the Common Achievement: http://warmetal.wikia.com/wiki/Common_Theme.
Disclaimer: I'm (obviously) mostly familiar with Imperial cards.
Hope this helps!
