I'm sorry if this is a repeat question, i did a quick archive search and didn't see anything on point...
Does the Blade-bound Magus qualify for the "Extra Arcana" feat at 3rd level?
"Black Blade (Ex): At 3rd level, the bladebound magus' gains a powerful sentient weapon called a black blade, whose weapon type is chosen by the magus. A magus with this class feature cannot take the familiar magus arcana, and cannot have a familiar of any kind, even from another class.
Instead of the normal arcane pool amount, the bladebound magus's arcane pool has a number of points equal to 1/3 his level (minimum 1) plus his Intelligence bonus. This ability changes the Arcane Pool class feature and replaces the magus arcana gained at 3rd level."
Does this wording mean that that this archetype doesn't receive its first Magus Arcana class feature until 6th level and therefore can't take this feat, or does this mean the "Black Blade" is a replacement Magus Arcana that is required to be taken at 3rd, and the Magus can qualify for the feat?
Edgar is right. They do not qualify for it at 3rd level. At 6th level, they start to qualify, so they can take it then if they somehow get a feat at that level.