Your armor and helmet really aren't important, if that deer starts hitting you then you've lost and you either need to get out of there or prepare to get KO'd. The agility armor removes from you may even make armor actively hurt you in combat. As a UAC fighter you need to keep your defense up while building up initiative. This means taking advantage of your maneuvers as much as you take advantage of your moves. Special moves are nice but what you're really aiming for is steadily building up initiative while blocking the deer's attack. Don't let him break through your defense by even 1 point, as that gives him combat advantage. CA lets them attack faster and makes you attack slower. Also they have like 30% penetration or something obscene like that so they more or less ignore your armor and just kill you anyway. If you didn't know, Maneuvers go off whenever your opponent uses a move or attack on you, as opposed to moves which go off on your timer. This can let you keep pace with or beat out a fast opponent.
Utilize Oak Stance, Death or Glory, Bloodlust, and Charge! up to 6 initiative and then add Flex to the rotation while removing Bloodlust in order to keep your defense high and your attack high. You need high attack in order to fuel Oak Stance. Only rotate bloodlust in after the deer has attacked as it cuts your defense in half; if you try to block with that you're dead. Death or Glory is a great way to speed up building up initiative. At 70 UAC you will need to keep your defense above 80% at all times or the deer will break it. Get up to 12 Initiative and then your options open up a bit. You can choose to go on the offensive and push your advantage like that or you can play defensively and build up combat advantage through moves and special moves.
To go on the offensive I'd actually suggest 14 to 18 Initiative Points. Your strategy will be to Punch, Flex, Flex, Flex, Punch, etc. etc. until their defense is as close to 0 as you can get it and then Knock His Teeth Out. Keep your defense up with Oak Stance during this. Repeat until it's dead. Don't drop below 6 initiative as that takes away your Flex. If you can Sting, do that instead of Knock His Teeth Out. If you feel like taking risks then use Combat Meditation as it is easily the best maneuver in the game. The problem is that if you don't know what you're doing it will kill you as it gives CA to your opponent. Try to use it twice to speed up your Charge! early on. You Really want to rush that 6 initiative. Leaving it on is a good way to lose combat though. Use it right before you attack so you can attack again immediately for maximum damage. Follow through with No Pain No Gain to be the ultimate killing machine.
Defensively, go to 13 Initiative, Invocation of Skuld, get back to 13 initiative and repeat 4 more times so you have 5 CA. With 5 advantage just punch flex your way to victory.
As for the damage formula being incorrect, I know we all figured that out awhile ago too. There were long discussions about it and everyone was trying to figure out how it actually worked but to no avail. I don't know what the current formula is based off of or how correct or incorrect it is.