Some random thoughts here:
First, thanks to Laxa for hosting the event. You did a good job.
Second, I think the Strengths and Weaknesses need to be tweaked. I wonder if the Strengths that give extra upgrades should be adjusted down. Calindu was a powerhouse with his 12-23 extra upgrades. I realize that's across 4 Strengths, but still, that's a lot of upgrades. That probably trumps any other combination of Strengths.
Also, some of the weaknesses that no one picks should be tweaked (like Lazy). I think every Weakness should be something that
someone might be willing to choose. There's no reason for someone to pick Lazy over another Weakness. If you made it something like "you get no Strengths until the final battle, but every win nets you 2 strengths", someone crazy might be willing to choose that kind of Weakness.
If you continue to have Lazy and Stupid as is, you should probably limit them as possibilities before the semi-finals (to avoid the loophole that several us took advantage of).
I think you should make it clear how the upgrade order works. Something like: First calculate Strength/Weakness upgrades (non-conditional), second add/subtract Arena upgrades, third add/subtract conditional upgrades (like First Blood, Revenge, etc.).
I don't know about others, but I rarely used my Style cards. I think I used my Weakness card more than my Style cards. So they hardly define the style of play we use. It'd be good to hear what others say, but it may be worth considering adding more style cards or giving better style cards to encourage their use (if they indeed aren't being used much).
I'm sure there's more, but that's all I can think of right now.