Simple suggestion so that all members of a Guild may access all Guild items without the possibility of theft.
Institute a method wherein Guild leaders and Officers can "tag" items to that specific Guild when they are placed within the Guild chest, and as long as said item is tagged it can not be sold by any method.
Of course, all items can be un-tagged by whom ever has the privilege to do so, and can then be sold as normal.
As a possible plat sink, this feature could cost a certain amount of plat to tag each item, based upon it's ML.
As a company revenue source - the feature itself can be sold via the DDO Store.