PH2, Legacy Items, and Assassins

[Goth Guru]

The Ninja in the party wants to drop his wizard level for
another ninja level.
In the Player's Handbook II it says it requires a quest.
I was wondering if it could include hunting down the
assassin from the Champion's Belt to activate the major powers
of the Legacy items, the Twins.
Since the Ninja has to give away the Talisman of the Sphere at the same time,
should I invent another Wind Duke site?

[Golbez57]

Why is the character required to give up the Talisman? Is that somehow significant to realizing the powers of the twins (I assume it's the kukri to which you're referring), or to restructuring his classes, or both?

[Goth Guru]

The one Wizard level is his only arcane level.
You cannot influence the Orb without at least one arcane level.
Another player says I should just put off the quest.