Basic concept a.k.a. TL;DR: Member storage for weapons/armor, but with more control over who and for how long takes items from it.
Guild Arsenal (GA) stores weapons, armor and costumes that are bound to the guild itself. Said items can be issued to guild members and then returned back to the Arsenal.

GA interface
GA gets its own interface tab at Guild Console. Guild members with right to control the Arsenal can issue and recall items from there, and players who are using guild-bound item can give it back early. Everyone can look at the list of items stored. Issued items can listed too, along with the names of knights using them and due dates.

Dispensing items
Guild members with priviledge to control GA can give out an item from GA to any guild member (called "user"), specifying due date.
For the user issued item will look like an untradable but equipable gear with expiration date.
There are two types of item users:
Normal user can equip the item issued, use it, heat it and forge it, but can't alchemize it, roll it's UV's or accessorize it.
Power user can do the same but including alchemizing, rolling or accessorizing. Resulting items will be guild-bound and will inherit expiration date of the old one.

Returning items
If item has expired, it will return to GA if any of these events happen:
* user opens Arsenal, standing on Arsenal Platform in the Clockworks.
* user returns to Haven
* user logs off

Aside from expiring on timer, privileged guild members can return the item forcibly. If it happens when user is in the Clockworks, he or she will receive a warning. If user does not logs off, returns to Haven or unequips the item in 10 minutes after receiving the item, user will be retain the item until he/she does so, but is forcibly removed from party and switched to solo mode. Items recalled are marked as returned and can be issued to someone else immediately. Switching to solo is necessary to prevent abusing recall system to issue one item to several knights in a party.

Of course, user may choose to return the item early via Guild Console.

Options
Guildmaster can set following (rank-based) permissions about GA:
1. Who can add items to GA. Only unbound item can be added.
2. Who can permanently remove items from GA and move them into their own arsenal. Regular unbinding fee must be paid to remove an item.
3. Who can distribute the items among other guild members and pull the items back.
4. Who can modify (alchemize, roll UV, accessorize) the items while using them.