Jandau said:
I'm fairly certain that it can be modded (if it's the PC version). Not sure how though, maybe someone else can help you, or you might try the official forums.
Beyond that, Soldiers pick either the Widow or the LMG, Infiltrators pick the Widow, everyone else picks Assault Rifles...
There is a way to do it on the PC version. It involves editing Coalesced.ini, but you need a special RubyScript file (which I found on the internet...somewhere. I can't remember) otherwise your game will go dead.
I
do know that you should be able to use the Coalesced.ini files from here [http://www.masseffectsaves.com/mods.php] without the Ruby Script thing, but you won't be able to edit them yourself like I can.
But yeah, Widow>All for Infiltrator. Claymore>All for Vanguard. I'd argue that the Revenant is probably>All for Soldier, but it's debatable.
Edit: on the off chance the OP has all of the stuff required for Coalesced editing, you want to find the line
"PlayerSpecialWeapons=(WeaponClassName="SFXGameContent_Inventory.SFXWeapon_MassCannon",UnlockPlotName="
Then replace everything after PlotName= with...well, a plot point. I used
Wpn_HeavyPistol2) (Remember to close the brackets!) which means you get the Widow when you get HeavyPistol2, aka the Hand Cannon.
Although I think I also get it earlier. So...eh, whatever.
You can do it for the Revenant (SFXWeapon_MachineGun) and Claymore (SFXWeapon_Flakgun) too. They should be around line 4000 or so, using Notepad++.