Weapons and armor are used by survivors to boost their attack and life. Each survivor joining the group starts with one armor and a weapon (both specific for their survivor class). If you retire a survivor you do not lose the equipment it has on. More and better equipment is found among the loot after missions or received as rewards after Daily Quests or as specific Episode rewards. Equipment can be upgraded or scrapped in the Workshop.
Each equipment has a level and a rarity (a number of stars signalling the upgrade possibilities) and possibly a number of locked or unlocked traits. The initial level also marks which minimum level survivor that can use this equipment and the level needed of the Workshop to do upgrades.
Note: You can have a maximum of 300 items (weapon & armor) in your inventory, the game will auto scrap items exceeding this limit. The current amount of items owned is indicated in your Workshop.
In the tables below each item lists the Damage or Protection it currently gives, the upgrade cost in XP and the alternate upgrade cost in Gold, as well as the amount of XP that is refunded if scrapped. Every equipment with a specific level and star count has the same upgrade costs and scrap value, whether it is untouched or upgraded to that level. Current damage or protection amount is also same for all equipment with a specific survivor class, level and star count. You can use the chart to see how much it will cost to maximize an equipment or upgrade to just a certain level and trait.
For example, if you want to upgrade a Legendary (gold/5 star) weapon from level 4 to level 5 (level upgrade does not change star count or initial level for survivor/workshop use) you can see the upgrade cost is 2519 XP (and additional time with the Workshop busy) or 29 Gold (instant upgrade). If the weapon was for Scout class, it will raise equipment damage count from 50 to 56 and unlock the level 5 trait if the equipment has one.
This table shows the upgrade cost in XP/Gold for one step up as well as scrap XP refund (in parantheses) at the initial level. It is the same amount for every equipment (weapons and armor). Upgrade time is the same for each level across the rarity columns.
It is not efficient to use equipment upgrades as an extra storage of XP (if XP storage happens to be full). Scrapping after upgrade refunds the same as would an un-upgraded item for that level plus 25% of what was spent on the upgrades. For example a 1 star level 5 has refund 330 XP and a level 6 refund 467 XP. The upgrade price of 3300 XP is thus not well spent for the 137 XP refund increase plus 25% of the upgrade (825 XP).
If you find exceptions to these rules, please make note in between (survivors type, equipment, Exp / gold).