1) Get the spider's kiss dagger.
2) Get 2 other weapons.
3) Equip the skd in your main hand.
4) Put one weapon in your off hand.
5) The thrid weapon in your inventory.
6) Switch the main weapon with your off hand (skd should be in your off hand now)
7) Switch your skd with your inventory weapon.
Cool You should have the bonus of your skd even though its in your inventory.