My thought was the ability to enter Touch Up on the items you have already crafted, and sign them with the Deaspected Crystals that have started to pop up. Also add the function to seal a Guild Crest onto your gear, so for example, a shield could have one applied to the face, a body piece could have the logo on the back or chest, a weapon could have the logo on the hilt.

The reason I think this would be awesome, is that the Guild Crest could be in itself a crafting skill up item. Would most likely be appropriate for either a goldsmith or a blacksmith to make, and it could consist of:

1x Iron Plate (for the backing)
1x Silver Plate (for the design)
4x Steel Nails
1x Deaspected Crystal

When created, it has the guild logo blanked, but will change depending on which player equips the weapon or item.