What does the lightning bolt icon represent?

The traps each have a lightning bolt icon next to a number. In other games this would indicate power, but they don't need power to run, right? What does the lightning bolt measure?

The lightning bolt on your weapons is simply a power rating. From what I've seen, it doesn't really correlate with much; the number you may want to pay more attention to is the DPS, as that actually translates to damage output.

For example, I have three different weapons with a 34 "power" rating:

Despite having the exact same power rating, the DPS between them is drastically different, and they do not perform equally well. On top of that, the Copper Founder's Raptor actually outperforms all three of these (from personal experience), yet it is given a lower "power" rating due to not being leveled up as much as the first three.

The takeaway from all this should be that this number hardly means anything. The weapon type and damage output are what you should be looking at. This number mostly represents how leveled a weapon is, but even then, doesn't give much information about the usefulness of said weapon.

The lightning bolt in the top left corner is your personal power rating. It also doesn't mean much, but it's based on your own FORT stats. Leveling up Survivors that are part of your Squads or purchasing stat boosts in the skill trees will raise this rating.

The power level is a great indicator of the actual power of the weapon. A higher pl would usually indicate a stronger, more powerful gun. For example, a Tiger at pl 20 is not NEARLY as strong as a Tiger at pl 82. The power level also can indicate what the gun is made of. Under level 34 is copper, 35-58 is silver, 58-82 is malachite... etc.

The DPS, while important, is not the number you want to pay attention to. DPS is damage per second. So this is only important if you are rapid firing the weapon and every bullet hits the target, which rarely happens.

The damage level (found on the first line of the stats) is the actual number that's important here. It tells you the specific damage that the weapon can do in one hit. This is what you want to use to compare weapons.

Now, with the new addition of the recombobulator and changing perks, any gun can be made into an awesome weapon, with right perks. You can change anything, with the right amount of gold, to have a "God Roll" or all legendary stats. This indicates a very high powered weapon.

That said, there are 2 levels for every weapon. There is the power level (indicated by the lightning bolt. When asked about the level, this is the number people refer to) and there is the 'star level'. This is what you use to level up the gun. So in your skill/resource trees, you have the ability to "buy" a 2/3/4 star level increase. This is what allows you to increase your weapon in power level.