UI suggestions to convey information people miss without a glaring tutorial.

[naive portal]

If we can't have text explanations at least make connected stuff be visualised as connected instead of misleadingly.
- NO - somehow else - yes

People miss that activesloting is a thing. Visuals show no ties to buttons, passive blends into the background and unslottable items show nothing.

To make sure people notice that something can be hovered over for more/any information, make the background of hoverable things brighter if the cursor is on the same height(not also width as this has to happen before someone hovers). Abscence of a difference and hoverless descriptions might give the impression that hovering is not a thing at all instead of optional. Pretty sure no image needed.

[naive portal]

It's not obvious whether perks are tied to guns or something else(technologies). If tech perks showed the technology next to them and guaranteed perks showed the gun then it would be players' fault for assuming there's no difference at all. The contrast between the type description and tooltip background is relatively low so missing the type is going to be overlooked.
Random non-technology can show a die or something that indicates they're completely random. There should be an icon for "added", but I failed to come up with an appropriate one and resorted to mapping the presence of an icon to the perk being present from the start.

[naive portal]

The last ability slot looks like an item slot and I recall someone asking why it can't be sold. Abilities are squares, items are round. These patterns make the current UI imply the utility ability is an item. Relocating it would help with that but cause complaints about weird item slot amount so I'm not suggesting it.

[haughty lake]

maybe some outline on unique perks for unique weapons, and other perks that were acquired after picking up a weapon - marked with some icon?

[naive portal]

As long as the icon implies "added" and can't be mistaken for anything else that's quite an upgrade to my idea.

Make tech perks circumvent the low contrast by including the tech icon in the type(bottommost text in tooltip).

[potent osprey]

Imho, it is next to impossible to miss the hovering mechanics. Even if we ignore a high chance of accidentally hovering over something, I am sure many people would try to click on items or weapon perks/attachments to see if it doesn’t something.

[spice creek]

The position of the perk should be enough to call out if its exclusive to the weapon or not.
IMO what you could do
is just have a sprite of the gun replacing the current icon of the perk

[potent osprey]

The weapon perks needs to be always on top. I like what Fibi suggested as well. Alternatively, don’t put gun/tech image, but instead place a small icon in a corner: a generic gun icon for weapon perks, ammo icon for tech perks. Bonus point for having a unique symbol/icon for deferent techs: SB, Ion, Laser. This symbol needs to be everywhere related to that tech, like tooltips, so people will learn what it means quicker.

[haughty lake]

I agree, but if you look at it from the perspective of a normal player who doesn't really understand what tech perks, unique perks, technology, etc, - you won't immediately realize that unique perks are always on top. Even I in my mod sometimes allowed that when creating weapons I did not always pay attention to the positions of perks, and it turned out that the unique perks were lower than tech perks.
In general, there is still an idea with the outline. Unique perk can be highlighted as something else, but to make the highlighting of different colors, depending on the rarity of tech perk, so that it was immediately obvious how lucky you are with the random tech perk. Just an idea

[spice creek]

they rarity highlight is cool but just a thin line between the icon and thenbox should be enough

[haughty lake]

sure, it just an example. Maybe even just background glowing enough

[spice creek]

background glowing might be too much
just something subtle

Imo the quickest way is this

Isntead of generic icon.
Weapon sprite in there

cant be more obvious than this

[haughty lake]

that would be much cleaner for identity, but sadly, some of unique cool icons will be missed, imo

[spice creek]

they can be re used for additional tech perks

[haughty lake]

thats too yeah

[spice creek]

They can look cool for sure but they sure dont distinguish enough from tech perks

[haughty lake]

yeah, most of them just a regular tech perk with different icon