Before I start sharing any opinions, let's look at some facts:

a. All blaster line weapons share the same stats in every way except damage type. The damage values are the same. This means that a Chaos set user with no UVs will take an equal amount of damage from Valiance and Arcana provided the two guns share heat level and damage bonus. This user will however take a bit more damage from a Riftlocker or Phantomos.

b. A 5* blaster with no damage bonus has a damage value of 252. One with Max damage bonus has a damage value of 314. A Knight in Lockdown has a minimum defence value of 100 in every damage type. A Chaos set, along with many other sets*, has the same amount of normal and elemental defence. The sum of the set is 125 defence in both types. A Skolver set has 142 normal defence and 125 piercing defence.

* You can tell by looking at the defence bars. If they're as long as on the Chaos set it means they're the same values as the Chaos set.

Let's start doing some maths. What you need to know first is how defence works, in simplified terms. Quite simply put, one point of defence removes one point of damage, making for a 1:1 defence to damage removal ratio. This is of course not the entirely formula because after all, a Proto Sword has a base damage probably less than 30 yet you can still do some damage against an Ancient Plate user with one. What actually happens is that once your defence is more half of the damage you're taking, the formula used to calculate the end damage is changed to a more complex one which never allows the end damage to hit 0.

Basically this means that once you start adding defence higher than half of the damage, it gets less and less useful. However, for a small amount of defence beyond the so called threshold, defence is actually worth more than one unit of damage removal per unit of defence. This is a very crucial part to discussing the balance of the Blasters, because half of their damage values is very close to a lot of people's defence.

Let's take an example. Compare a Skolver set to a no damage bonus Valiance, as was common some years ago. You got about 250 damage vs about 150 defence. Half of the damage of Valiance wasn't even close to the threshold, and thus Valiance was pretty well resisted by everyone.

Enter the BKCs, and suddenly there's a lot of people with high damage on their Valiances. You see, Valiance now had the potential to be a significantly stronger gun. With a BKC and Shadowsun Slicker you had a base damage of 303 and no one had enough defence to reach the threshold, with the exception of two groups. Ancient Plate users and people with UVs.

A max UV is worth 25.6 units of defence. Pushing past the threshold on a Skolver set was actually quite easy and only required a very small amount of UVs. A single high was enough to push past the threshold and Valiance damage became a lot more trivial. This is what the meta looked like for I believe about two years. Valiance was one of the most popular guns but it was significantly more effective against people without UVs than those with it.

When the gunner update arrived, a lot of people got new Blasters, obviously. A lot of people also looked down on these as overpowered, criticising how they're able to kill a striker off in just 5-6 shots. Let's make some comparisons to see the actual changes, though.

To a Chaos user, there's no difference between being hit by Vali or Arcana.
To a Skolver user, there's about half a pip's difference between Vali and Riftlocker. Arcana and Vali have a difference of about 1 pip.
To a normal damage UV'd Skolver, the difference is several pips more, as explained why earlier in this post.

So to summarise, the gunner update's new blasters only significantly affected people with good UVs - those without them hardly notice it. If you're complaining about OP blasters then it's probably because your defences have been put closer to people who don't spend as much resources on LD gear and you've lost a bit of your gear advantage.