Path of the Blade allows up to two attacks if you go by Dragon 381.
Both Dragon and Dungeon are official magazines. You don't have to use their content, but they are condoned by WotC. The guide that you posted is not official in anyway and should be read keeping that in mind.
The Path of Blade attack power can be found in Dragon 381 on page 69.
You can shift a number of squares equal to 2 + your
Charisma modifier. Two times during this shift, you can
make an attack, each time against a different enemy
adjacent to you.
It calls out the 2 attacks within the power as a primary attack and a secondary attack (against a different target than the primary target).
Path of the Blade allows up to four attacks if you go by the 4e compendium!
This power is not reproduced exactly in the 4e compendium! Perhaps your guide was referencing the power as written in the compendium.
Effect: You can shift a number of squares equal to 2 + your Charisma modifier. Two times during this shift, you can use the Path of the Blade Attack power, each time against a different enemy adjacent to you.
The attack power in the compendium has a primary and a secondary target (so up to 2 attacks each time you use this power). It is unclear whether there was intent to change the description when it was added to the compendium. I suspect this was a mistake, but your table will have to decide which versions of official resources to use.
I asked about Dragon & Dungeon vs the Compendium as a followup.