What 2XP of an upgrade can buy varies a lot from card to card. What do we get here in comparison to the Level 0 Mauser C96?
- Costs 1 fewer to play (3 rather than 4)
- Has a icon as well as an one
- Has an addition +1 when firing (for a total of +2)
- Has a bonus on succeeding by 4 or more.
The first of these is always nice but is completely standard.
The second (a bonus skill icon) isn't much to write home about - "you can now discard your 2XP investment for a +1 in two out of four skills instead of just one" is pretty much the most meagre possible boost you can give a card
The extra +1 while fighting is actually more beneficial than usual, because of the succeed by ability. Most equivalent upgrades e.g. .45 Automatic to .45 Automatic (2), in gaining +1 , basically say "there's one value in the bag that changes from fail to success" (or "you need to commit one less to this to be at everything-but-autofail"). For the Mauser, the +1 does that but also gives you a second value in the bag that goes from "succeed but no bonus" to "succeeds with a bonus". This can actually cause the effect on a good number of tokens, so it's pretty valuable.
In contrast, the additional text (the bonus on succeeding by 4 or more) is actually a bit lackluster. Passing by 4 isn't a trivial task with a +2 weapon, even for a character with decent base skill. Moreover, you generally know whether you need to ready the gun with it's oversucceed bonus in a turn or not, and in cases where you don't, getting to ready it in addition to the resource you were already getting for oversucceeding by 2 is basically pointless. So the only time this meaningfully triggers is when you oversucceed by 4 in a fight where you still need to fire your gun again this round, in which case you now gain a resource as well. Personally, half the time that sort of situation occurs is when I'm fighting the boss of a scenario and throwing everything in to a test anyway to be sure of hitting before drawing a 0 - which is exactly the sort of time I usually don't need an extra resource!
So overall - it's not a bad upgrade for only 2XP, but the most valuable parts of it are actually the -1 cost and +1 when firing. In a class with a wealth of XP options such as Rogue I'm not convinced it's likely to be a first choice upgrade, unless you're playing an odd Down the Rabbit Hole build.
Excuse me, I need to go and check Dexter's base combat value...