1. Remove the gremlin/undead/fiend bonuses or what have you.
2. Reloading the clip = stand completely still
3. Hitting an enemy grants a tiny buff, only long enough to last until the next 2 shots are fired
4. Shooting the gun at all makes the knight travel slightly faster
5. Hitting with the bird on the charge grants the entire party with a single 30 second MSI orb
*Obsidian carbine receives a higher rate of poison, but does not give any MSI to the user when shots hit.
That would be the idea- to reward skillful play with the MSI ability and separate the antiguas from other strafe n shoot weapons.
Skillful?
You don't even need to do much, just shoot 5 times ANYWHERE AT ALL, wait a second, and repeat for a permanent MSI buff.
That's not exactly "skillful".
You have to hit things to get the full MSI buff, you have to make sure that you don't run out of clip or you'll stand still, and you have to know where you're going with it which requires some foresight. Just shooting the gun would give you a tiny MSI buff of about a low, but hitting with it would grant you a much larger and more meaningful one, akin to the orb you pick up off the ground.
Sounds good and all but those monster perks are what balance it out with the OC (not that anyone uses the Sentenza anymore thanks to the numerous max damage sets we have).
If you were to do this I would include the OC in the MSI buff but I would reduce it's damage a bit to be like the Plague/Blitz relationship where the poison one only matches the pure damage one in power when poison is applied. With this you would actually have the Sentenza viable again while not leaving the OC out in the cold.
I kind of addressed obsidian carbine in the OP. My thoughts on it are that it's already a very well defined gun but that it could do its job a bit better in general.. so instead of MSI for the user it just poisons things somewhat reliably, think 2 of every 3 bullets as that would make it highly unlikely for the gun to not poison things while still making it somewhat random. As is, it's very easy to go 4+ clips without managing to deal any poison, and that's kind of unacceptable given the nature of the status effect and how weak the gun is compared to others.
A damage decrease would mean that one always outclasses the other dependent on the situation and amount of damage being taken away. Think about blitz and plague needle- blitz is always better if it one shots or there are no healers and plague is always better if there are healers around to finish them off where blitz would have done much less because of it. This is a decent sort of balance, but an uninteresting one that often leads to players always choosing the more damaging variant over the status.
The OC does have reliable poison, you just need to use the charge attack which would be ok had not the charge forced you to stand still for a long period of time.
But this is identical to the rest of the antigua line (except the Duelist and the Base Antigua) the charge attack for all of them have the capability of dealing much more damage than the regular shots. I would actually compare it to the Iron slug.... it has a 2 shot clip but the regular bullets don't have much chance to inflict status (Alchemers have a similar chance but thanks to ricochets it has more chances) while the charge deals more damage and has greater status chance.
I would give the OC the speed buff and the damage reduction but I would like to see the status chance on regular shot increased (to be more on par with the other status guns).
Reliable poison on the normal hits, dog. You can stand there and fire off an entire clip at one enemy while tanking as much damage as possible but I think I'll pass and just use venom veilor if I seerusly need to. Your balance tweak would be fine for it but again I'd still rather they not go with the damage for status trade since it basically doesn't work.
Shoot 5 times - Wait until clip reset = Permanent MSI buff.