Wizard of the Spiral Tower
There are a few separate issues involving the Wizard of the Spiral Tower, all revolving around
Corellon's Implement.
Corellon's Implement: Choose an arcane implement that you specialize in, whether the wand, staff, or orb.
This means that anyone who multiclasses into wizard cannot utilize this class feature. While this may not be an error, if this is by design then the Paragon Path should have the prerequisite "specialized in an arcane implement".
You can use a longsword as if it were that type of arcane implement
Per the rules for Reading a Magic Item, specifically the Power section (page 226), the keywords of the longsword's power can be attached to any spell cast that uses the longsword as an implement. For example, a frost longsword can be used to make
any spell cast have the cold keyword, and thus activate feats like Wintertouched and Lasting Frost. Is this intentional?
when casting your spells.
Last issue - in addition to not working for multiclassers, this class feature doesn't even work with specialized implements as written. None of the Staff of Defense features can be used with the longsword, effectively negating the specialization that is required to use this class feature. Furthermore, the ability of the Orb of Imposition to extend an at-will spell effect is done separate from the casting of the spell, and thus would not work. That's one implement that is completely useless, and a second which is limited. Only the Wand of Accuracy works at full effect with this feature.
I would highly recommend that the wording be changed to allow full use of Corellon's Implement with a single specialized implement, or perhaps even allowing multiclass wizards to benefit (as not allowing them to do so limits options for the classic 'gish').