A feature should be added allowing for the creation of an object or structure capable of storing valuable items such as gold, currency, precious gems etc. It should be accessible only by guild leader or individuals within a guild who are granted access to it such as a treasurer or military general. It could have an extended authority/claim duration such as 72 hours.
Recently the guild I'm with is recruiting many new people and security has become a concern. Rivals on a server can create alt characters in an attempt to infiltrate the guild in order to steal items. As it stands we have one of our guild mates claim a warehouse every day so only that person has access to it aside from the guild leader who can open anything on a claim. Having a vault and being able to allow access to multiple people would make things easier.