Ah. Well playing with a small party is pretty challenging unless you know the game very well. I'd probably go with a full party, at least if you plan to play more difficult content like DLCs and megabosses. Some of the DLCs are pretty good, the megabosses are just kind of pointlessly difficult encounters but I still like the challenge.
So Shards of Woedica is an interesting weapon though I've never used it. As a club you can use the modal to decrease a target's will by 25. The "shards of woedica effect" also increases damage taken and you can either give the club to a tank with the "Blessed Defiance" upgrade, but IMO "Coordinated Escape" is more interesting. This allows you to give the club to a non-tank who can wade into the fray, debuff an enemy, not get engaged, and flee. The will debuff is especially useful to ciphers but there are priest and wizard spells that target will also. Even some paladin abilities, like Glorious Beacon. The higher level "sacred immolation" and upgrade abilities target reflex, so you might consider having a character with a flail. There are some nice flails like "sun and moon" as a stat stick, and sungrazer for its ability to cancel recovery as well as stun on crit. Flail modal debuffs reflex by 25.
Looking at your party...
I've played probably 80% of multiclass comboes but never actually played a fanatic. A berserker/paladin would have good armor (+2 from frenzy's hardy, +1 crush/slash/pierce from thick-skinned, +1 from exalted endurance, and eventually +3 from stoic steel). Should have decent defenses with deep faith. And has some self-healing options with lay on hands and eventually savage defiance. The health loss from frenzy eventually gets to be pretty bad but it is manageable. It's too bad carnage isn't like in POE1 where the Shards of Woedica effect would be distributed to everyone hit by the carnage. Anyway, you should take spirit frenzy because it applies stagger on hit, and this will trigger the SG passive so a SG attacking the staggered enemies gets back health. Don't upgrade it to spirit tornado (ability is buggy). You also definitely want blooded, not just for the damage bonus but because it is one of the only ways to gauge where your berserker's health is when it is concealed. If the blooded effect is active it is under 50%. Your character will make some comment about healing when he first hits 25%. You can also script him to self-cast lay on hands when near death. I'd take the other barbarian passives and savage defiance / stalwart defiance. On paladin side there are many options, definitely take exalted endurance. Liberating Exhortation is quite useful, as is Reviving Exhortation (unless you're expert enough noone ever dies). The willbreaker would also be an interesting weapon choice for woedica themed party since it is a punishment-themed weapon, and it debuffs will as well as the modal debuffing fortitude, both of which would be helpful to your ciphers. Also if you take the brute force ability as a barbarian you can target fortitude instead of deflection. Deflection is normally lower, but staggered from spirit frenzy
Trickster/Unbroken is fairly straightforward and should make an okay tank / fighter. I find enemies don't break engagement that often. I'd consider the devoted subclass because it offers +2 penetration and +25% crit damage with your weapon of choice which would help with damage output especially if you want him to use 2 blunderbusses anyway. If he's meant to switch weapons a lot you might consider black jacket, which can remove the delay from switching weapons and gets an extra weapon set. Unbroken is good too but best on tanks, and this character won't have enough armor to be a great tank, though probably good enough for regular POTD.
Priest of Woedica will be good as long as he/she doesn't run into combat unbuffed. Priests are fantastic and have some of the best party support spells like devotions for the faithful, champion's boon, spiritual ally (has unlimited heals), consecrated ground, barring death's door, and at higher levels I'm a fan of spark the souls of the righteous. The writ spells are extremely powerful debuffs as well. Writs of war and sorcery can shut down a lot of enemies, but even the humble writ of engagement is useful. And the writ of mending gives mass enfeeble which is extremely powerful.
Stalker/beguiler is interesting. I've played seers quite a bit but not this specific combination. IMO...if this is a melee character you're better off with soul blade. If not, you're probably better off with ascendant or psion if you don't mind the redundancy. Also if it isn't a melee character, don't take stalker. I'm guessing since you picked stalker it is melee, and soul annihilation provides fantastic burst damage on hard to kill enemies. Beguilers are best at spamming low level spells, but psions are just as good at that, so I don't see a lot of reason to take them unless it's just for variety. For cipher picks I listed most of what you want below, it's generally the same stuff you'd want for the spiritualist, but also take draining whip, hammering thoughts, lingering echoes, and the empty soul (last two take with spiritualist also). For ranger picks, I recommend the bear as an animal since it is the tankiest and attacks pretty fast. Take vicious companion and resilient companion. Protective companion and Stalker's link give big accuracy buffs when you attack an enemy the animal is threatening. Also want at the least heal companion, revive companion, evasive roll, and marked prey. Concussive Tranquilizer is nice if you have room. Predator's Sense can give your companion a big damage boost, provided there is a damage over time effect, and ciphers have lots of DOTs (soul ignition, disintegration), and there are also weapons with DOTs like I'd recommend Stalker's Patience. It fits thematically but is also a very powerful spear with bonus damage on flanked targets from ambushing, mortal wounds provides a constant stacking DOT effect, and best of all mercy strike has a 33% chance to attack again on crit, which means you can often get double, triple, quadruple strikes, or more (which is extra great as a seer since you will gain a TON of focus). Seers can stack accuracy higher than any other build so you should basically always crit. Marked Prey is +10, Stalker's Link is +10, flanked is +10, Survival of the Fittest is +10 (when active), borrowed instinct is +20 (keep this spell up ALWAYS), and psychovampiric shield debuffs resolve by 10 making it effectively +10. These all stack for roughly +70 to +80 accuracy on top of whatever you get from equipment. I'd consider one-handing stalker's patience (or whatever if it has good on-crit effects), that's another +12. If your accuracy is high enough from the other things you're already always critting, then use a shield or dual wield. Other weapons with good on-crit effects- aldris blade of captain's crow heals you, sungrazer stuns, ball and chain prones, magistrate's cudgel is particularly good for its "judged" marker and is soulbound to ciphers giving 3s stun on crit. I'd probably use stalker's patience and magistrate's cudgel, either dual-wielded or just switching weapons after an enemy is judged.
Troubadour/psion is a build I've played a LOT and it is fantastic, very versatile, on chanter side there are many good picks but you probably want summons, thunder rolled like waves on black seas, and at the sound of his voice and upgrades. The instruments of death are ultimately the best summons but until then the wyrms are good damage and the ogres are solid. For chants you probably want thick grew their tongues, ancient memory, and many lives pass by. Beyond that it is more specific to what you are trying to do, and the resistance chants can be very useful, or the damage chants (mith fir), or sure-handed ila if you have a lot of ranged characters, especially if using weapons with reloads since sure-handed ila applies twice on reload weapons. On psion side, you want at least one charm spell, psychovampiric shield, mental binding, secret horrors, soul ignition, body attunement (situational), borrowed instinct (always up), echoing shield, pain block, tactical meld, disintegration and ancestor's memory. Normally you want brisk recitation on so you can cast more invocations but it depends on the situation.
Overall your party looks pretty solid. It's a good combination of tanks, support, and damage, and I think you'll be able to do all the content provided decent gear choices and stat spreads.