{Honestly, "Anima inanis" isn't a really good pseudonym.  But if it's 
 going to be used that way, the second word should be capitalised as 
 well.}  

Dark soul.  Indifferent, cold and deadly.  He was working as an assassin

for almost six years and he was one of the best alive. 

{"He had been working as an assasin".  I'd delete "alive"}

 Daniel chuckled at that last statement.  [Soft.]  He had shot his
last female hit two times, one in the heart and one in the head.  She
had
begged for mercy but the hit specifically said "dead".  Unfortunately,
it
was point blank with a .50 cal AE Desert Eagle.  The remaining pieces of

her head were sprayed about the wall behind her dead carcass. 

{You are working too hard here to gross out the reader while squeezing 
in exposition.  If you want to do this effectively, then start with the 
hit in question, actually show it, then have him go back home, take a 
much needed shower, and get his next target. Incidentally, only an idiot 
would do a pointblank execution with a Desert Eagle.  He would have been 
covered with her remains after her head exploded, very conspicuous and
rather distasteful.  Guns, especially that gun, are designed to be used
at a distance.  A professional wouldn't use a maximum calibre handgun 
anyway for a job like that.  Too much noise, and just how dead do you 
want your target to be?  What, is he compensating for some sexual 
inadequacy?}

 Ripped apart by multiple full auto AK-47s during a
botched hit on a terrorist leader while I was still a part of the CIA.

{Oh stop it.  You're being silly.}

 Picking up his glass, he quickly downed the rest of his drink.
[Maybe I will be able to retire, after all,] he thought, obviously
amused at such a prospect.  He poured himself another drink.

{To whom is it obvious?  Nobody else is there.}

would miss their target.  The Desert Eagle was nowhere to be seen.
Along with her would-be killer.  [That was too close], she thought,

{Sentence fragment}

behind her crate and tackled May down, as the gunman fired.
She felt pain as the bullet sliced through her leg.  They

{She won't really start to feel the pain until
the initial shock wears off as I understand it.  First there's a 
sensation like you've been punched, then you go numb.  I could be 
wrong though.}

were both on the ground and now she was wounded.  She looked
up to see the gunman standing only five meters away, with
his Desert Eagle pointed at them.  And her CZ75 was nowhere
in sight.  It looked bad.

 But he didn't shoot.

{Pardon me.  <WHAM!>.  Just what is this moron trying to do?}

He just stood there.  He didn't say a word.  She
noticed that May held a grenade now but he could have
easily disarmed her before she could use it, and May knew
it too. 

{Oh really?  How?  He's five meters away  That's more than 15 feet.
Just how would he disarm her, as opposed to just shooting her?}

guy is a ghost and he's way out of your league.  Apparently,
his being here just assures me of the fact that the drug lord
has noticed you and wants to put a stop to your actions.  I want

{The "drug lord" deserves a name.  So Roy thinks that Mr Big sent
out an elite (but strangely erratic) hitman to shoot all his henchgoons,
screw up the hit on Rally, and leave 20 million bucks worth of smack
for the cops?  What, did he look at the script?}

this thing can deliver was right.  Doesn't deform, incredibly
armor piercing but because it doesn't deform, doesn't do too
much to flesh.  But then, with a head shot, it doesn't matter

{Except of course punch quarter sized holes in it.  Ever see that
Fearless Fosdick poster?  "Fortunately, they are all flesh wounds!"}

five by ten meters.  Daniel could care less about the cheap and
tacky wallpaper that coated the walls, nor could he care about
the old and peeling paint on all the furniture.

{No, he "couldn't" care less.}

like himself.  His mind didn't think in that way, however.  He was
pure efficiency. 

{You're kidding, right?  Didn't he notice the way he screwed up the
hit just a few days ago?  Efficiency my butt.}

The scope came to life, the display showing Rally sitting in her
hospital bed, perusing through a Guns and Ammo magazine.

{Why are the blinds not closed?  Delete "through"} 

{A couple more thoughts.  Rally would have been interrogated by the 
police as soon as she was lucid, and given this guy's phallic obsession, 
it would be very easy to link up all of his hits which means Roy would 
have a fair bit to say about our boy's M.O.}