4 artifacts  mana curve:16 1-cost 19 2-cost 4-4cost
4 bonesplitter
3 lightning greaves/leonin shikari
19 creatures
4 loxodon gatekeeper
3 nezumi shortfang
4 samurai of the pale curtain
4 leonin skyhunter
4 auriok steelshaper
16 Instants/sorceries
4 duress/wrench mind/distress
4 cabal therapy/orim's chant
4 blackmail
4 last gasp/terror/rend flesh
21 lands
8 swamp
9 plains
4 mirrodin's core"

I'm sorry, but I'm having trouble reading this decklist.  Does "3 lightning greaves/leonin shikari" mean 3 Lightning Greaves or 3 Leonin Shikari, or 3 of each, or 3 total of each?  And why did you list them together like that; are they serving the same purpose in your deck?  It sort of made sense for "4 duress/wrench mind/distress" (which by the way is a good base of discard spells), but I'm really just confused by this decklist.  The best I can really do is retype the whole decklist as I think it ought to be.

First, you say that "only 7 of your creatures are Soldiers or Knights, so you use Auriok Steelshaper instead of Glorious Anthem".  I think a better substitute would be Veteran Armorer.  And with the Armorer, you wouldn't really need the Equipment subtheme at all, so the Shikari can go.  Two copies each of Bonesplitter and the Greaves will still be good though.

Your creature base is good, but Samurai of the Pale Curtain and Leonin Skyhunter both need double white, so in a white/black deck they may have trouble coming out early.  As for the Shikari's replacement, try Mourning Thrull- a quick flier that can pad your life total early on.

Now, for your non-creature spells.  Everything looks fine, but I want to replace Rend Flesh with Mortify for added versatility.  Also replace Wrench Mind with Castigate, because when forcing a discard, choosing the card your opponent discards is always better than letting them choose, and removing it from the game is good too.  I don't particularly like Cabal Therapy either, unless it comes right after a Castigate.  I'd say make them all Orim's Chants.

And as for your land, replace the Mirrodin's Core with Orzhov Basilica.  Trust me, you'll like it better.

Now for the decklist:
4 Loxodon Gatekeeper
3 Nezumi Shortfang
3 Samurai of the Pale Curtain
3 Leonin Skyhunter
4 Veteran Armorer
4 Mourning Thrull

2 Bonesplitter
2 Lighning Greaves
4 Duress/Castigate/Distress
4 Orim's Chant
3 Blackmail
4 Last Gasp/Terror/Mortify

8 Swamp
9 Plains
4 Orzhov Basilica

Well, I got it down to 61 cards, but I just don't know which card to cut one of.  Maybe it's not necessary to cut one.  The deck should run pretty well this way, but you did express concern over Hideous Laughter and Pyroclasm, as well as type match-ups.  If the Laughter and 'clasm punch through Veteran Armorer's bonus too often, try upgrading to Oathsworn Giant.  And for type match-ups (games against decks very similar to your own), try Hand of Honor and Hand of Cruelty, or Sword of Light and Shadow.  Other cards you might try:

Charge Across The Araba
Conjurer's Ban
Orzhov Guildmage
Pillory of The Sleepless
Manriki-Gusari(to stop opposing Swords of Fire and Ice)

Good luck!
~BMoor