As long as you aren't an avid trader who enjoys dealing with traders who value unidentified weapons, identifying your weapons is one of the most important things that you can do in this game. Weapons that are identified can be sold to the in-game shop owners for more marks and it reveals the full stats of a weapon, allowing you to see if the weapon has any rare attributes and to determine whether or not you should consider holding on to it.
Identifying your Weapons
There are five ways in the game to identify your weapons:
Going to Bill Smith's Weapon Shop is by far the most common way of identifying your weapons. It only costs 40 marks to identify a weapon, which is more than worth it because unidentified weapons can only be sold for 1 mark. Even if you don't want your weapons and are too lazy to identify them, identifying them is still a good idea because you know if you have weapons with rare attributes in your possession. Also, if Bill Smith is willing to pay more marks than usual for a weapon, it's likely to have a rare attribute.
A slightly less common way of identifying your weapon is to go to Shortleg Smithy's Weapon Shop in the Forest. Smithy requires you to pay him 60 marks for each weapon that you want to identify, and you should only consult his services if you've ran out of quests and are stuck in the Forest. You should also keep in mind that Smithy often pays less for your weapons than Bill Smith does.
Using an Identify Scroll is another way to identify your weapons. These scrolls can be very useful if you're ever stuck somewhere; you can use these scrolls on your unidentified weapons and decide which ones to apply Oils to. However, similar to other scrolls, the Identify Scroll is never guaranteed to work 100% of the time.
An uncommon way of identifying a weapon is by using a Quartz. A Quartz is identical to an Identify Scroll, but you need to have at least 2 mage skills in order to activate it. If you don't have the mage skills that are required to use a Quartz, it may be a good idea to sell your Quartz to the in-game shop owner because they're worth more than an Identify Scrolls. You can use the marks to buy Identify Scrolls instead, which don't require mage skills to use.
A fifth way of identifying a weapon is by being in a clan that has the Armor and/or Smith ability or equipping a weapon that has the Armor and/or Smith attribute. Doing so allows you to identify weapons and/or armour from your backpack without cost.
Not every single weapon in the game can be identified. The most basic of weapons, such as Rusty Daggers and Leather Jackets, don't need to be identified in most cases. However, it is guaranteed that every single weapon that comes with a rare attribute will need to be identified. So when you find that Rusty Dagger that needs to be identified, there's a chance that you may have found a rare Rusty Dagger.
When weapons are unidentified, you don't know if they've rusted. For this reason, it's a good idea to identify all your weapons due to the possibility that they'll disappear because of excessive rust. That, and you can't go to the Armoury to polish weapons that haven't been identified yet.
Leave it to the Traders
There are usually traders on the Trading Post forum who are interested in buying unidentified weapons. If you are the type of person who often does business with such traders, perhaps it's best if you avoid identifying weapons altogether and ignore everything that I've written.