@LightningYu
You are clearly overthinking this.
And you are also falling into the trap of thinking that stats alone could “save” a single mastery class which, speaking as a player who basically sorts through and juggles item affixes/components/augments/devotions all day, is utterly ridiculous.
Your whole “the game forces you to pick two classes” argument hinges on the assumption that you simply don’t gain enough stats to play as a single mastery class, and that trying to circumvent this somehow counts as trying to game the system - which doesn’t make sense considering how easy it is to beat mastery stats using just suffixes and components. That assumption also hinges on the devs making masteries absolute - which is clearly wrong considering how many builds these days are even defined by the items they use (hell, the loading screen even says so). Items are THAT powerful, and they’re only part of your sources for stats - there’s also augments, devotions, and of course, stat gain from leveling.
Food for thought:
Consider that Arcanist mastery gives you 500 total physique/cunning/spirit and 1150 HP/1500 energy.
A single “of the eagle” suffix on a non-accessory slot gives you roughly 120 physique/cunning/spirit, so 4 instances of such a suffix basically gives you the extent of physique/cunning/spirit bonus from masteries. A single Mutated Scale component gives you 180 base health and +3% health. 5 of those plus a base health of 1250 (250 default and an estimate of 1000 from your base mastery) gives you a total bonus of roughly 1.2k health. Congrats, you’ve almost beaten mastery stats. Now instead of just fixating on items, try to distribute that stat gain through all the various sources of stat gain you have - levels/devotions/augments/components and gear - and try to account for the fact that you don’t need to raise all three of physique/cunning/spirit (unless you’re trying to build a heavy armor gunslinger/caster - and I definitely wouldn’t suggest going single mastery class for that).
Now, you might try to argue “but dual-classes should get even more stats from your sample setup!” True, but that’s beside the point. If you ask around or try to check out the build compendium, people don’t just stack stats endlessly with their builds - they aim for breakpoints. This is what I previously referred to as a baseline, like 10k HP is generally seen as acceptable for ultimate. Your challenge, as someone trying to make a single mastery build work, is to find a way to make your extra skill points count considering the extra work you had to do to reach ultimate difficulty breakpoints/baselines.
It’s also extremely presumptuous to argue that a single mastery’s worth of skills can’t possibly be enough to create a viable build - which would imply a SEVERE imbalance on the part of that specific mastery, and which would affect ALL classes that include that mastery.
If a mastery was underperforming that much the devs would be trying to fix it.
@Zoso
I normally don’t expect more from the average forumer than what they can obviously deliver but since you like sticking around, I’m going to address this now - you simply do not have game experience or knowledge to even make such an assumption, so I question why you keep repeating it.
I would suggest just playing the game since the info I gave out earlier is pretty much already obvious for people who have tried to make builds like these work, and is mostly for the benefit of experienced players who have simply been devoting most of their focus towards other things.