The idea of this character is more to take the attacks, but dodge or parry the hits
. As I mentioned, higher than average AC should more than compensate for somewhat fewer hitpoints.
The easiest comparison is to the paladin and cavalier, since they're also Con tertiary. A swashbuckler will have 3 less HP at 1st level, 13 less at the beginning of paragon, 23 less at the beginning of epic, and 32 less at 30th level. In return, even if the paladin or cavalier is wearing plate, the swashbuckler still has 2 more AC.
Anway, thanks for the comments
. For the at-will prone trick, perhaps something similar to the bard's jinx shot
, e.g. "once before the start of your next turn, when an enemy triggers nimble guardian
by attacking an ally, you can choose to forgo making a melee basic attack. If you do so, that enemy falls prone."
I'm also planning on adding a few tricks that allow swashbucklers to get on well with warlords (mainly because I have an Essentialised warlord in the works too). There are couple of such tricks already; for example, knowing that his adjacent leader is about to make a brash assault
, the swashbuckler uses his parrying trick
. When the warlord's target makes a counterattack, the swashbuckler then not only makes a counterattack of his own, but reduces the damage of the enemy's attack. (And finally a nearby striker steps in to launch his own attack against the enemy.)