Prepare for a wall of text that i might or might not have re-read and corrected.
TL;DR: the charmer class is useless when your goal is to optimize a party for crushing hard mode; the charmer class's point is to give players who want to tease their enemies to victory a way to fulfill their fantasy. Also i did a lot of geeking about support builds in this porn text-based game.
In my previous answer I answered to "Who is Stylish meant for?" (namely players that want their character to tease their enemies into submission) and how to fill in the gaps of a build that entirely revolves around the tease damage that Stylish amps up, but I see that your question here is rather "Why would I play tease for damage when I can play thief to fulfill the damage role better?"
I'll try to answer your secondary questions first:
- Stylish indeed only cares about your chest armor being light (likewise, Veteran's heavy version only procs if your chest armor is heavy or if you wield a shield, it doesn't care about other equipment).
- War Song only scales off of Presence (if memory serves right it deals 20 + Presence / 2 damage). It uses base accuracy (agility * 2 + non-weapon-equipment accuracy) against enemy mental resistance, and base penetration (your strength score) against enemy focus (it doesn't use temptation). It can crit, but overall its damage scaling is indeed rather poor, but War Song's usefulness is less its damage and more the 5 turn long AOE debuff that can ensure a lot of reliable Twist the Knife procs for a thief pc (imagine a thief that starts its turn with a mind rapey performance), and also Etheryn: Outrider and Cait: Hexblade.
- As for the dagger as a starter item, i, too, think the new wooden rod would be a better starter item for a charmer, but consider this: charmers already get a nice off-hand catalyst, so giving them a main hand catalyst too would give them much more value than the other classes (white mage acolyte and black mage arcanist only start with a wooden rod for example). Also the dagger has a nice roleplay flavor (an easily concealed self-defense tool for an outwardly happy-go-lucky charmer), even though in a such a setting, a wooden rod could also fulfill this roleplay flavor but i'm rambling. Also the dagger gives +5 evasion which no starter-area one-handed primary weapon catalyst does, and the only starter-area one-handed weapon that gives more evasion (the javelin at +10) would feel quite awkward for a character that is meant to be a sexy enchanter. So you could see the dagger as giving an "evasion vibe" to what is meant to be a backline class (backliners need evasion), rather than doubling down on spellpower.
- If you are looking for burst damage, dual wielding dagger is not really optimal. With the off-hand penalty, i think it only has 52 base damage i think, and it's all penetrating which sucks because enemy tanks have 25% resistance to penetrating damage. I'd suggest Galon's Griefmaker for its 50 armor penetration and its split damage profile, and get Belt with a Pouch to offset the -5 initiative penalty of griefmaker's heavy weight. Although mind that griefmaker is an outlier and will get nerfed-adjusted in the future, just like Bessy Mauler in the latest patch. The wooden rod / metal rod / fire rod are actually good damage weapons (and fulfill the "gun" fantasy, at least for me), but i'm already digressing.
But now, i'll talk about what role a charmer has in a "competitive" party, and what does Stylish have to do with it. Spoiler: it's going to get convoluted, because this class is firstly meant for the roleplay potential of playing a (sub-optimal) character that wants to tease everyone into submission.
So the optimal role that the charmer wants to fulfill is to be the party's support. And by support i mean damage amplifier + enemy debuffer and
not healbot, otherwise white mage would be better. Prime example of support recharge powers are Blessing, Song of Storms (with the infamous blessed song of storms combo / exploit), Grease, Crackle Powder, Blinding Beauty. The most support-y of encounter powers is Resplendent Aria, but i'll go back to encounter powers in a sec. For at-wills, the only support at-will that is not an outright healing power (and would thus justify going for white mage) is Song of Courage, which amps up the whole party's Attack Power by your own Presence: at level 6 it's a party-wide +17 to +20 (depending on your starting choices) Attack Power boost! And while toggling Song of Courage
does heal your party, the heal is so meager that it does not justify healbotting with it, but more on that later.
So at that point, while a +20 party wide attack power buff might sound cool, bear in mind that you're a charmer support so your basic attacks aren't relevant (otherwise you'd go for light warrior or thief to boost them), and one of your companions has to be a healbot because you are not, so their basic attacks aren't relevant either. So really Song of Courage is about giving a +20 attack power bonus to your tank companion. But now it's time to talk about encounter powers. See, if you want to play support, you have to max Presence, because it gives you Leadership, which in turn gives (at level 6) +40 attack power to your tank and +40 spellpower to your healbot. But Leadership and Presence are also what your summons base all their stats on, so if you're playing support then you want a summon, which will take up your encounter power slot. Most summons (at least Wolf Spirit and Phyria) use Attack Power for their actions, so now your Song of Courage benefits your tank
and your summon! Also, i've tested it, and max Presence + Leadership equipment makes your summons actual powerhouses, averaging 70 damage per turn (post-mitigation) on their own.
So here is the typical "competitive" full support build: Song of Courage, 2 support recharge powers (blessed song of storms for fireworks), and a summon encounter power, and you're maxing Presence (for overall damage boost) and Willpower (for song of storms), and going for all the Leadership you can (bear in mind it's capped at 100, but currently you can't reach that). Now we've finally arrived at the question: why go for the charmer class for this if it only gives Sexiness?
Well, at this point, we have a build that is fully dedicated to boosting your party's damage, and that's a given. We might want to compare a thief pc's damage to the damage that a support pc gives to their party, but i think it's more of a choice of tactical approach: do you want direct enormous damage (thief), or do you want good damage with relevant utility (support). But now is the time to choose a class for our support build:
- Thief and light warrior don't cut it, because we already max Presence and Willpower, which means we can't max both Strength and Agility too, which are mandatory for a plain weapon damage build. Unless you count on getting drunk at Garth's every morning but that's a personal choice. Also you can't go for Agility + Willpower spellblade because your at-will is taken up by Song of Courage, and Song of Storming yourself wouldn't be optimal because, as you're dumping Strength, you should have less Armor Penetration than your tank.
- Black mage would be useless because you simply have no spells.
- White mage would have a minor utility of healing you a little bit each time you toggle Song of Courage.
- Charmer gives you more sexiness to boost your tease attacks, which you might as well use because you're already maxing Presence so you might as well use the Sexiness it gives you, and your simple attacks with no Strength + Agility won't do as much damage as tease.
So really, after having developed this whole support build, the choice comes down to:
- a meager heal when toggling song of courage, which you don't need because you have a healbot companion and you're not frontlining;
- better tease which is the best thing you can do while waiting for your recharges to cool down and toggling Song of Courage feels useless.
So here you have it: the point of Stylish and therefore the charmer class in a "competitive" party, is to have better things to do while playing support and waiting for your recharges to cool down.
But i prefer to see the point of Stylish as enabling players who really want to put enemies on their knees by wiggling their hips while their tank is getting gutted and maimed in the frontline.
Also, finally, bear in mind that if you play support, then your priority is Leadership over Sexiness, and the only chest armor that gives Leadership is Conqueror's Breastplate which is heavy armor. So if you play support optimally then you can't even benefit from Stylish. So right now, with the current equipment available, the charmer has indeed no point if you're going for a party that is optimized for crushing hard mode.