I did not know any of that, so... fair enough. Now I wonder if there's anything else on the table, should Stone Warden actually make it to the base game like I had heard long ago. There's no shortage of class mods and oozemancers seem pretty set in their role as the go-to OP class even post nerfs.
DG's stated the stone warden will go non-donator when a new donator class is introduced. Dunno if he's changed his mind on that since, but that was the original stance on it. Pretty sure there was even a blog post on the main page about it.
It seems you need to increase several stats at once to really get the better of your skills , the early game available skills deal only very weak damage in comparison to early game of other class, but you need to prioritize Dexterity because without enough dexterity you're going to miss more than 50% of your strikes and skills hits.
You need dex for stat reqs and it's not a bad idea for dagger scaling, but for accuracy that's what the combat accuracy
talent is for. Just stick a point in that whenever you can and hitting stuff won't be much of a problem at any point in the game (barring the occasional extreme defense anomaly). This... is what you do with every melee class, ever. Also, most stuff that says its chance to effect scales with dex... actually scales with accuracy. Or did, anyway.* That and "scales with magic" (actually scaling with spellpower. I think the game's better about that nowadays.) was one of the more notorious "the tooltip is lying to you" things for a while. Check the code!
*Actually, checking the tooltips it does look like it's better about not lying to you. If it says you just need accuracy, accuracy is all you need. Dexterity does increase that, but so do a number of other things. Combat accuracy is obvious and largely sufficient for a long, long time, but there's also dexterity gloves and a handful of other egos to keep an eye out for (steady, I think "of the archer", probably others. Weapons of balance, of course, which are doubly good for a marauder if they're going defense tank).
Their main purpose of the early skills is to stun/confuse, but as every effect skill you can only hope it will work on the enemy as if he's generated with high immunity, you're wasting stamina and turns while getting damaged.
From my test you only start to get decent damage once you get Flurry, +/- at level 4
If you're going daggers, a couple points into the dagger mastery passive will have you doing plenty of damage to clear out the first tier dungeons and make the second tier ones more palatable. By that point, as you note, you've got access to flurry and pretty much anything else you'd be interested in having and should have plenty of damage options. A GWF flurry is a thing of glory and awe, if you choose to kick open battle tactics (and you probably will, eventually).
So any tips to make early Marauders game less of a big pain ?
You're fine until level four (I've regularly beat Prox with sub-10 accuracy and basically no active talents on adventurers. It takes a while, and a lot of kiting while you regen, but it's very possible.), after which you can pick up a point or two in fast metabolism. I find a decent amount (5-10) of passive regen massively eases the game up until Daikara or so. You've also got the option of cracking open tactical (as a cornac) and starting down the defense-tank path, which Marauders are pretty good at and mostly trivializes the early game. You should be mostly fine just stabbing crap with knives, though. Trawl the stores for some steel or massacre iron and the damage should come naturally.