I know that there is a Knight in D&D 4e, but I want to know where the detailed rules are for this kind of Fighter. I want to check if it has some other powers than the one I have from a template.
The Knight is found in Heroes of the Fallen Lands, or I linked to the DDI description if you have access to that.
It is a fighter variant. This means you can replace Knight powers with Fighter powers of the same (or lower) level.