Is it safe to sell old gear (armor/weapons)

[Hotdogcrisis]

I'm about 3.5 hours in and haven't sold anything as I'm not sure if you upgrade old gear yet. Thanks.

[Doresh]

Armor appears to be pretty safe to sell.
Weapons you might want to keep around, if only because you can only change your weapon's appearance based on the weapons you currently own.

Either way it also appears you will always be able to fast travel back to old shops in case you want the gear back.

[thejuiceweasel]

There's a thing to know: it seems like you can only equip the look of a weapon if you own it. I sold a weapon because I found a duplicate, and when I sold it, I couldn't use the look of the weapon anymore for other weapons.

Clothing is just a stat thing it seems, but weapon looks, yeah, if you wanna collect 'em all, keep the weapons.