Standard Soldiers

My current T2 Soldiers Deck:

Lands
21 Plains

Creatures
4 Akrasan Squire
4 Elite Vanguard
4 Veteran Armorsmith
4 Knight of the White Orchid
3 Preeminent Captain
3 Ranger of Eos
3 Captain of the Watch

Non-Creatures
4 Harm's Way
4 Path to Exile
4 Honor of the Pure
2 Martial Coup

Sideboard:
4 White Knight
3 Celestial Purge [only have 3]
4 Oblivion Ring
4 Soul Warden

Easily, I could take out a Harm's Way for that 22nd land. In a deck like this, I'd rather be mana flooded than mana screwed. Especially if you want to support that Captain of the Watch, I would go as far to include another. 23 seems to me to be the right number. You won't miss too many land drops and given some Knight of the White Orchid shenanigans you can get to 6 mana pretty easily and even reach that seventh land drop to have Martial Coup's full effect.

Soul Warden seems awesome against the Kithkin decks as they have Processions. Gaining 3 life off of their spells is a nice little tech. Even against opposing Bitterblossoms, makes Faeries race a bit harder.

My little brother made a Mono-White aggro prototype and maybe less Martial Coup and 2 more Baneslayer Angels makes your curve very sexy. Ranger of Eos, Baneslayer, Captain of the Watch? Makes this a force to reckon with.

You rightfully guessed Sould Warden's purpose. Kithkin might be faster, but soldiers are sturdier (Armorers makes Volcanic Fallout/Infest pointless to Soldiers). It might be enough to stall until Soldiers click in. I was considering Guardian Seraph for this but, Soul Warden is a 1 mana drop (tutorable by Ranger of Eos) and nets good life with Soldiers (Preeminet Captain = 1 life each swing and Captain of the Watch = 4 life).

I dunno about Harm's Way getting axed a bit, though I 100% 2 more plains wouldn't hurt. Harm's Way is white's bet combat trick in years, if not ever.

As for Baneslayer Angel, yeah, it needs an air striker but Baneslayer Angel is worth a lot of $$$ now (20-35 each), not worth it IMO. Maybe Battlegrace as a cheaper alternative? She also lends her Lifelink +1/+1 boost to another creature as soon as she drops, but Exalted might go against the Weenie theme.

I have to disagree. 21 is the right number because of the Knight of the White Orchids. If you up the land count you'll be behind the l;and count by turn 5 or 6, by that turn you probably only need it to cast a turn6 bomb which is not worth it. You have Path to Exile that works as land search sometimes. Keep the 21. You'll be on the play even if you were on the draw most of the time. I would move Martial Coup to the SB. They only shine against Elves but with Path and Harms Way they aren't needed. Move 2 Soul Wardens main deck so you have a way to outrace other aggro decks and they don't hurt the theme of the deck.Also since you have no Spectral Possession which I think you should, you can play at least two Gargoyle Castles they will ensure Wrath effects are not so sexy and have some gas for the long game. Everything else seems fair enough.

P.O: Go for 22 Lands. I agree with Koby in moving the coups to the bench, you wont really need them in more than half of your matchups. On the other hand, playing 21 lands is risky, even with the Orchid Knights; you still might get may 1 land starter hands, and this deck cant risk not pulling the second land. In this deck I might play 1-2 Gargoyle Towers. Now for that last slot that would be missing if you benched the coups and uped the land count; I would put the 4th Captain on there, since he can be considered the biggest threat come declare attacker step. Still, open your decklist possibilities to the upcoming Zendikar set, and start testing new cards in the list, who knows what might be pulled.