You wanted more concise details, so here they are! Now please stop leaving flaming poo on my doorstep, no matter how hard I try I can't resist stomping the thing out, and nobody likes a poo covered foot!

So anyways, here is the compiled list of weapons changes for Gears of War 2:

Arm your gears: New and
updated gears of war 2 weapons

New Weapons

Scorcher Flamethrower:
Dooming your opponents to a burning and painful death this beauty
only appears once per map. You can also extend the length of your
flame with a well timed active reload.

Gorgon burst pistol:
Two clips of burst fire goodness, perfect for when you are using a
meat shield or using the new shield item

Shield: This new
Defensive item goes hand and hand with the new burst pistol and to
give it an even great range of use, you can slam into the ground for
use as instant cover.

Poison Grenade: This
new grenade releases a cloud of death good for forces foes from cover
right into your bullets

Updated Weapons

Lancer assault rifle: A
meeting of two chainsaw attacks now results in a race to see who can
mash the B button the fastest, the victor getting a nice satisfying
chainsaw kill. You can now also chain saw people from behind but
watch out you are now longer untouchable while splitting someone in
half.

Hammerburst Assault
Rifle: Based on how you pull the trigger you can now effect how much
kickback the rifle has and how accurate it fires. The Rifle also does
more damage per bullet

Smoke Grenade: The once
kind of unless smoke grenade is getting a nice buff. The smoke
grenade now comes with a concussive blast stunning opponents. Now any
grenade can stuck to walls and set up as a trap.