grips n what not...

basically i see people selling weapon upgrades n stuff. yet not selling the weapon? i do not understand..

example i found a axe and it then got identified and then it said axe grip bla bla....

but then if i went back to look for that same thing it is not in my inventory, yet people can sell these things?

You have a chance to salvage Axe Grips and other weapon components from the weapons itself with an expert salvage kit. (not guaranteed)

When you identify weapons, you may UNLOCK weapon upgrades. Expert Salvaging that weapon MAY give you the weapon upgrade(most likely the unlocked one). Some weapons may be identified to unlock 2 upgrades but it will give you only one upgrade component or other things like crafting materials when expert salvaged.