Cool deck! +1 from me.

WHAT TO TAKE OUT:Aerial Guide and Mighty Leap are not very good because most of your creatures already have flying.Slither Blade doesn't really seem to fit with the rest of your deck.Cartouche of Knowledge isn't great for the same reason as Aerial Guide. I think Cartouche of Solidarity is ok, but I would not run 4, so you should probably only run 3.

WHAT TO PUT IN:Definitely go up to 4 copies of Angel of Condemnation. This card is AMAZING value at only 4 mana, acting as a good attacker and blocker, as well as a form of removal. 3 Dauntless Avens (There is no picture for this i guess) have a better effect for this deck than Aerial Guide. Add an extra copy of Angel of Sanctions, as it is just such a great card. Judging by the decklist, I am guessing that you are trying to make this deck safe from rotation. However, I would run 4 Kitesail Scout to replace the Slither Blades as a low cost flyer. This card is only like 5 cents, so the investment is worth it.

With these suggestions, if my math is correct, these changes should bring you to 36 nonland cards. I would just cut 4 Islands and 4 Plains to bring you to 24 lands.

OTHER SUGGESTIONS:If you are willing to spend some extra money and don't mind rotation, Archangel Avacyn  ^Flip is an awesome pickup for your deck. If you need more finishers, Glyph Keeper is a heavy hitter and is hard to get rid of.

Nice deck! I hope my comment helps :-)

yea 32 lands is overkill, control decks only run ~26 and your an aggro-midrange deck with an average cmc of 2.44 ... 23 lands should be more then sufficient (especially with no real demands for leaving mana open) but you can get away with 24 if you prefer ... (i would drop 6/5 islands and 3 plains)

that being said, it feels like you have a main goal, then alot of filler cards that seem redundant or dont really do what you need them to do.

cards like Aerial Guide, Aven Wind Guide, Mighty Leap and Cartouche of Knowledge give flying to an already mostly flying deck, and Slither Blade, Fan Bearer and Cartouche of Solidarity are okay but feel like they belong in a different deck, with a different goal.

[dauntless aven] does feel like a good fit for the deck, and you can shift the deck to make cards like Aven Wind Guide more useful with cards like Oketra's Monument to make the ability more relevant, and Glyph Keeper as a solid finisher.

id also consider running some countermagic, even if its just Supreme Will, Turn Aside or Failure and maybe consider Cast Out.

Any cards that buff up creatures?

in u/w? for the most part pump spells tend to be in green or red, but there are a few

Retreat to Emeria and Collective Effort are probably the strongest, while Tenacity and Make a Stand have their uses. ill also give an honorably mention to Temmet, Vizier of Naktamun, Unconventional Tactics and Tandem Tactics from the standard non-g/r pool.

What if I added a 3rd color like green for pump spells, how would I go about adding them?

Standard U/W Pump Spells (mostly) (gatherer search parameters "target creature gets")

The only ones worth note in HOU are Act of Heroism and Unconventional Tactics

Seeing as you have embalm creatures, you could always try In Oketra's Name as a cheap buff for all of your creatures.

I'd also recommend Gideon's Intervention for the sideboard of any deck running white... once you know what your opponent's playing, it can often disable their win-con or just be used as protection.