Perhaps the use of cosmetic weapons could accomplish what you're looking for if Turbine added a new section for such items to the 'Equipped Traits' setup panel. If they were to add a new section like this, you could slot those weapons there. Doing so would add the cosmetic weapon's appearance to your character, just like slotting a skin in the 'Appearance' section does now. The actual buff or 'effect' of the weapon could perhaps be treated like a weapon-specific corruption???
It would be nice to see creeps get more build options!
Casinoari - Rank 15 RK - Arkenstone
Malakorou - Rank 10 Defiler - Arkenstone
Casinari - Original Challenger of Saruman Minstrel - Arkenstone
Casithir - Rank 11 RK - Evernight