Saeviomagy
Adventurer
That would seem to prove that your reading is incorrect.I try to read it in all kinds of ways, but the only one that makes sense to me is 2 attacks, where the first might trigger a "secondary" if conditions are filled.
What bugs me is that there is no damage specified for this "secondary" attack.
If you don't have the special weapons, the power reads:
Encounter Martial, Weapon
Standard Action Melee weapon
Primary Target: One creature
Attack: Strength vs. AC, two attacks
Hit: 1[W] + Strength modifier damage.
The second "hit" line is the damage for the secondary attack, because each primary attack triggers one.
The alternate reading is if you don't pay heed to the indentation, and read the power as always granting you a secondary attack, regardless of the primary attacks: the problem with that reading is that the secondary attack would have to be listed under "effect:" in that case.