I see you have made him a Dex attacker like the rouge but not made him use light blades. This is both good and bad - it gives versatility and allows many fighting styles, but it runs counter to what most people think of as a fencer. There is nothing to prevent this guy from picking up a really big axe and going all out for damage. (Agile defense is after all just a weaker version of a large shield, and many fighters don't use shields). Having him start with only simple melee but adding rapier proficiency, while making the powers only work with light blades is a start. You can then add a feat that allows the use of any weapon. The cost to use an unusual weapon would then be two feats - one fr proficiency, one for the special "can use non-light-blades with fencing" feat, which seems about right.
Yes I think it should be an encounter power. Prone is, I believe, too powerful an ability for an At-Will.What where do you think you're going were an encounter power?
But in 4E there is no "graying" of the line between action types. A move action is supposed to be movement oriented. This ability should be a standard action.Charismatic feint is a "power-ization" of the improved feint feat from 3e.
my problem with the feint as a standard is that it is far less useful. i would be tempted to move it down to a minor action instead.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.