Have ben playing the game since launch and tried out each of the professions. I would like to suggest opening up the weapons more across the classes. I would love to be able to equip a rifle on a thief or a ranger. Engineers should be able to use a hammer or mace at least to recalibrate equipment and enemies. Staffs can at least be used by non-magical professions as clubs or quarterstaff style, harpoons-spears would be great to have outside the water and anyone should be able to pick up a pistol.
I understand that there would be some need to play balance these weapons and abilities across the game that fit the style of the class, but I think it would add new life to a lot of people that are getting bored with the limits they have reached so quickly with characters they have invested so much time in.