At the risk of sounding rude, should you be trying to rebalance PSO if you don't know something like this? ^^;
I thought you mean't a single adept unit breaking spirit, not the abuse case of stacking multiple effects like it. And that was pretty rude, but ill forgive you ;3
Even if I didn't know I got you guys to keep me right. Whats more important is my experience with previous rebalance mods (of which I've done a few) and my interest in game design rather than specific knowledge that I can pick up by asking questions.
Its also worth noting that this rebalance project is primarily for my own benefit, as something I would enjoy playing with IRL friends. I am sharing this because I care about this community and feel what I am doing is interesting, not because I view myself as being the best and only person for the job. Thats why I bother to ask for input at all, rather than just making changes and saying "Deal with it" ;3
On the topic of Adept itself, I will consider removing it but it is an interesting item. And were the power of Spirit lower it also wouldn't be that much more powerful than the other TP affecting items/weapon specials in the game, and the drawbacks of stacking them (Rather than things like Battle units, a Stat maxing unit, potential V50X or V801 units, Cure units, important specific resist units etc) is pretty high.
I would argue that the deciding factor is not the risk but your ability to use the attack. Berserk continues to work when you reach the minimum HP value of 3, thus allowing you to deal double damage forever, as long as you don't get hit. Charge also has effectively unlimited usage, since 200 Meseta is nothing compared to the capacity of your wallet. Spirit, on the other hand, stops working when you reach the minimum TP value, thus forcing you to use a fluid and limiting the number of Spirit attacks you can do without piping to restock. Sure, you could use a Geist weapon, but the time spent stealing TP negates the extra speed of using Spirit, so you'd be better off just using NHH the whole time -- unless you factor in Adept, which allows you to stretch a single TP bar much further and thus could potentially impact the calculus of whether Geist and Spirit together are worthwhile, i.e. further study is needed.
When you compare the three attacks, Charge is clearly the most overpowered, as it poses no risk and has unlimited usage within the context of a single run. Berserk involves risk but has unlimited usage, while Spirit poses no risk but has limited usage, so IMO that makes Berserk and Spirit equal, while Charge is in a separate class. You can't very well adopt the "use sacrificials on everything" playstyle with Spirit if you burn through your fluids before you finish the quest. Berserk is more dangerous, but it can be abused indefinitely. In some sense, one could even argue that this means Spirit should do more damage than Berserk.
These are good points, however you need to factor in the fact that no encounter will last an infinite period of time. Partly because this is impossible (as enemy HP is capped fairly strictly) and also because sacrificial specials by their very nature make the encounter faster.
If you can defeat a boss before you run out of fluids (which is very likely as both a Tech and a Spirit user if you are equal to the content you are doing) then Spirit is in this case mechanically identical to Charge in that all you lose is money with little to no actual risk in the fight itself.
I'm inclined to agree on the subject of spirit maybe needing more power than it gets, as it is a resource that can easily be depleted (which goes back to the point I made on techs) since your ability to use either is dependant on you stuffing your inventory with fluids so you're able to continue on, and if you're like me and hate wasting time going back and forth through shops, you then also rely on luck with getting difluid and trifluid from drops just to finish a straight run.
The issue of TP is also one I have provided a specific 13* unit to solve, one that gives you the stack-overflowed TP Regen value. TP stealing specials have also been buffed to provide more ways for Tech users to save money or avoid wasting time while working through levels or be able to push harder content where running out of fluids is highly likely. This is a large part of the reason why I wanted to give Force's higher ATA so they could better use mechanics like this.
Techs also are helped out a great deal already due to the fact it doesn't take 20 RAfoies to take down a group of enemies on solo ultimate anymore ;3
I'd say that if access to these changes comes soon, try testing the two as equal damage outputs and having charge more expensive for just a little more damage than a hard attack and see if that feels balanced in play.
I may consider leaving Spirit and Berserk at the same multiplier (especially since I don't even have the tools to change that yet ;3) but I still feel Spirit is the more consistent of the two and by far the least risky. Berserk requires a certain skill level on the part of the player to use indefinitely, and players with that skill probably won't find PSO very hard unless I balanced around them which would exclude the rest of the player base (including me : P.)
So in the context that Berserk is actually still dangerous, it should probably be the most powerful or no-one would use it unless forced to (Such as being a CAST.) People managing to abuse it anyway in this case are also being rewarded for being good at the game which I don't view as being a bad thing.
Unlike Charge which is effectively the same as Berserk but without any of the skill required. Arguably Spirit is the same, however you cannot stockpile the used resource to the extent you can with charge.
So perhaps, like I said before, a more balanced Charge would work fine within this dynamic, as the safest but slowest option for improved damage at the cost of accuracy.
Whatever the case this topic is academic since I can make none of the changes suggested yet.