A Carenza is a display, a flow of strikes and moves strung together to showcase ability and skills ... Originally, I'm sure, to put the fear of the gods into an adversary, and perhaps save having to fight them at all.
Just search on youtube and you'll see a whole bunch of them .... most of which, sadly, fail to put any kind of fear in me.
There are a few, a very few, which have the desired effect, that seem to come from a different place, a mind and body that can imagine a real adversary that they are trying to impress. There's a different will, a different intent, and it comes out in the movement in stark contrast to the rest. (And yes, it's usually in footage of 'the old men').
So how do they differ? Well, obviously real experience will change your intent and will manifest in the movement ... but what is there to see that makes it physically more believable?
Many people mistake speed and fast movement for skill, twirling and swishing the weapon really fast in endless combination as though that is intimidating ..... What they lack is the understanding that there is a natural rhythm to the thing - power strikes take longer that twirls used to distract, offensive and defensive moves occur at different distances from the body. Fakes, baits and inserts also have a rhythm all their own including enough time for them to work, or not, and sword edge placement, and cut mechanics, are important for each, and every, cut.
These changes in cadence, the body mechanics of power, and the difference in range and intent from offense to defense need to come out in a Carenza for it to be believable - it means you understand what you are doing and are not twirling your weapon round as fast as possible with no idea how it works or where the opponent is.
Oh yeah, and don't look at the floor or randomly into space whilst you concentrate on how good you look .... look at THEM, use your eyes to lead their attention to where you want it to go - Engage!
After all, a Carenza should not be for you, it is a message to someone else.
Make them believe it.
And to do that ...? Yes, sorry, you do actually have to understand, at least somewhat, the game you are about to play. Not only that, you have to understand yourself and your role in this theater.
My Carenza will look totally different from someone of a different size, gender and personality. It needs to make ME look like a threat, and it needs to make me look like a threat to THEM.