Allow any weapon that can be/has been crafted on to have additional effects added to it via Hilt Wrappings.
These Hilt Wrappings would be handwraps converted for the purpose at a trap station, and would be used just like an augment is used (double click, drop weapon into barter box, etc) and would add the min level of the wraps to the min level of the weapon but still cap out at 20. Named wraps could be used as well, but only wraps with a min level of 20 and below would be eligible since the weapon caps out at 20. Only magical effects would be applied, such as vampiric, while non magical effects, such as silver threaded, would be lost....you're not smacking the enemy with the hilt after all.
Example:
Take a silver longsword and disjunct it for crafting.
Craft Holy Burst of Vampirism on the sword to make it a Silver Holyburst Longsword of Vampirism, Min level 18
Now take some handwraps and craft acid burst of stunning +8 for ML 10 wraps
Convert the handwraps in the trap crafting altar to Hilt Wraps
Add the hilt wraps to the longsword via the barter window to make a Silver HolyBurst and Acidburst longsword of Vampirism and Stunning +8, ML 20
The level boost from the wraps would be their base level, so putting mastercraft on them would not reduce how much is being added to the weapon's ML, but mastercraft on the weapon itself would still work just like normal.
If in the example above the sword were crafted as Evil Outsider Bane instead of Vampirism, for a ML 10, adding the wraps would still make it ML 20 but a mastercraft could then be applied to drop it to being an ML 18 silver holy burst and acid burst longsword of stunning +8 and evil outsider bane.