MTG Salvation

I went to two prereleases this weekend. In the first (midnight), I went Temur and despite a mediocre pool, built a U/G deck splashing R and went 4-0, effectively "winning" the event.
I was stoked and vowed to do just as well in the second prerelease, going Jeskai this time. When I saw my pool I thought I was sure to go 5-0. Sage-Eye Avengers was my promo, but it only got better from there - Monastery Mentor, Citadel Siege, Shu Yun, the Silent Tempest, Cloudform, and 3x Sandsteppe Outcast were just some of the highlights.
I went with an agressive U/W deck, going for consistency, but lost my first match to a horrendous misplay. Opponent was attacking with a Rageform manifest and hit it with Ruthless Instincts to make it 4/4 and trampling. I untapped my Wandering Champion with Refocus, then cast Feat of Resistance to give it pro red. Turns out Manifest tokens are colorless - whoops! I did alright after that until match 4, when I overextended into a Crux of Fate and proceeded to go 3-2 for the event.

Though I'm sure part of my record was due to bad play compounded by tilt, I can't shake the feeling that I could have done a better job building my deck. I sometimes found it hard to use my amazing cards. I therefore have two questions. Within the U/W framework that I had, could I have built my deck better? And with the pool I had, could I have chosen my colors better?
Deck is organized by Creature/Noncreature, then CMC. Pool is organized by color, rarity, then notability (Sandsteppe Outcast above Aven Skirmisher).

The Deck


Curve:
1
2 CCCSSSS
3 CCCCCCSS
4 CCCSS
5 S
6 CS
(this counts Will of the Naga as a 4-mana spell)

The biggest problems I noticed after the fact was that I really should have been playing Pressure Point (perhaps cutting a Refocus) and that my three-drop slot was a litle overloaded (though with all the awesome three-drops in my pool, it was hard not to play them all).
In the games, I often had trouble curving out and often found myself with five great cards in hand but playing one a turn thanks to a lack of mana. Maybe an extra land would have helped?

The Pool

Black looks great with Brutal Hordechief, and Green had some good cards, but I figured I wanted to be consistent on mana so I could always play my awesome spells. Maybe not the best approach?

You're a bit light on creatures, which can hurt in getting run over. The easy thing to do is cut runemark for either weaponmaster or scion. I wouldn't be against cutting channel harm in order to get the other in as well. I'm not against going a bit more into red for warden/master the way but I understand the appeal of being two colors. Your deck isn't exactly how I'd build it since I would go a bit creature heavier. TBH you almost have the free splash for horde chief who is gross and you could do that and eschew red entirely. Point being I think you need more than 13 creatures considering almost none of your spells are hard removal. Sometimes you just get bad beats too

I would make the following changes:

Yeah I agree with merls changes. Although if you're adding two more red sources I'd consider adding in master the way. Really solid card. Although you do want to have the mana for it to use it before you dump your hand. I'd also drop runemark before a second refocus.

I would cut a land for a Pressure Point. I went 3-1 with a 16 land list with a higher curve than you and I was running 3 cheap cantrips instead of my 17th land. I also think that you were unlucky to open a small amount of removal. A Sandblast would have helped your deck a lot.

I think Avengers is a bomb and is too good to cut in a base blue deck. How your mana is makes the black pretty free if you add red (nomad, etc) so I'd add brutal and the red cards and just play all your bombs.