Late to the party, but I just tried out the 2H version of this build (#2), and wanted to share my experience/considerations.
First off, I forgot to get Berath's Blessing, because I'm dumb. Also, I didn't get the GotM, nor the Effigy (is it even possible to get the latter, on a solo run?).
Trials of Iron: NO
Gear-wise, I got almost exactly what's indicated.
Armor: Reckless Brigandine
Weapon: Whispers of the Endless Paths (only upgraded to superb because I can't obtain 4 kraken's eyes, and with offensive parry enchantment)
Neck: Charm of Bones (+2 INT)
Belt: The Undying Burden (+1 CON)
Ring 1: Voidward
Ring 2: Entonia Signet Ring
Hands: Gauntlets of Ogre Might (+2 MIG)
Cloak: Cape of the Falling Star
Head: Helm of the Falcon
Boots: Boots of the Stone (+1 DEX, +1 RES)
Food: Mariner's Porridge
Other that these minor differences (well, not so minor, especially the lack of BB in my build), I built it exactly like indicated. It is worth noting that the build was so weak at start, and skillchecks out of my range, that most of that gear I couldn't get until very late in the game (lvl 16 or so).
Lvl 1-5, an absolute nightmare. I didn't have any gear, going through the first caves (I could only kill 2 beetles and 2 skeletons) sneaked through the rest) and the ruins on Maje island was mental. Especially in the ruins, I couldn't fight ANYTHING at all, or I would die. So I crafted some firecrackers and managed to distract&sneak past.
Level 6-13: once you leave Maje Island and get to Neketaka, it's a breeze to just do talking or courier quests, plus exploring all the hotspot on the nautical chart (LOADS of XP), and you'll find yourself at level 12-13 in theheal blink of an eye.
Level 13-17, a big slump: just spent going around, killing whatever crappy ships I could find for loot and xp, trying and failing to advance any of the 200000 quests I had active. I just couldn't complete any: either enemies were too strong, or the quests required to pass skillchecks that I didn't meet (especially mapping quests or quests that involved access to remote parts of some islands, which lay beyond some "checkpoint" event). The total lack of sneaking also makes this build very hard to play. I was on the verge of quitting/rerolling a bunch of times.
Llevel 17-19: total PWNAGE. Jump into a group of 20 mobs, pop those buffs, and watch them suicide against you (courtesy of the sword's proc). Fights take a looooooooooooooooong time, especially so in TB mode, but you'll beat most stuff: positioning is essential, and sometimes going offensive on healer/caster enemies is required. After the first 16 levels or so of struggling and not being able to fight squat, I was having lots of fun at last! I finally could kill some stuff and actually progress some quests. Dinged level 20 before I even knew it.
Level 20, very late faction quests and endgame. Well, it's back to the nightmare. Some of these quests are basically impossible, some are extremely hard, and some I cheesed via sneaking.
Main issues: early on, it's very hard to even hit mobs. Later on, that gets better with gear, but the damage output is too low. Dunno if it's because I missed those extra 4 points in MIGHT (BB+GotM+Effigy), or whatever. I hit the enemies most of the times, misses or grazes were reasonably rare, but the damage I dealt was risible. Most of the times mobs just "suicided" against Whispers' effect. Later on, the suicide keeps going, luckily, although not as much with proper end game enemies (they'll actually hit or graze you for very low damage, but that doesn't make them "suicide" and that's what got them killed for me, using this build). Furthermore, enemies from the very late parts of the game actually hit you for real damage, and although the build is great at survival and dragging out fights, we're back to the damage output being too low to kill stuff before the fight is TOO long and you use up all your lifesavers and eventually just die.
Here are some notes and examples I noted down as I played through the game:
At level 16:
Beina = no go
Katrenn = no go
Old City = no go
Nomu (bounty) = doable
Tahae (bounty) = doable
At level 17 (finally obtained the Whispers sword, and a decent armour, although not the Reckless Brigandine yet):
Rathun ships/mobs = no go
Hanging Sepulchers = no go
Eamund the Fox = doable
Ikorno = doable (took about 20 rounds to take down the ironclad construct)
Mutiny = doable, but left me completely crewless and I struggled to recruit any more
Broodmother = doable (not the broodmother herself, but the "checkpoint" encounter that's on the way to her)
Bardatto family extermination = doable
Lady Epero = doable (Lord Admiral Imp and Katrenn too, but the guards kept aggroing and I could have taken them on but I didn't want the negative rep, and for Katrenn, I knew the fight VS the constructs would have lasted like 300 rounds, and I couldn't be bothered. I skipped these two, luckily I had other stuff I could do, by now.)
At level 19:
Hanging Sepulchers = still no go, the group of mobs North-East is just too beefy and has too many healers
Giant Grub = easy
Old City = clearable
At level 20, with full gear:
Drowned Barrow = absolutely no go, got rekt in no time
Maw: splintered fortress = no go, I could fight a couple of isolated patrolling rathuns, but had to use sneak to avoid pulling the big groups
Drowned Barrow = got rekt
Aeldys = took me a couple of tries, but managed it (you need to get lucky and not get turned into a piglet by their casters)
Fight VS 2x VTC ships during the approach to Ukaizo = no go
Ukaizo Guardian = lol no. 15 rounds and I took maybe 10% of its health, I was out of everything, and then he regenerated.
Ukaizo Sentinels = no way. They could hit me for 40-90 damage a pop.
So, in the end, I'm stuck: is there any way to skip the Ukaizo guardian AND the two sentinels? I managed to avoid the former by letting it engage the fleet during the scripted event, and just sailing forward, but the sentinels still spawn and they see through stealth...
Soooo, this was my first solo+potd attempt ever and I'm a total noob: do you guys have any tips on how I might get through this? Respect? Change of gear? Would the extra 2 points in MIG from the Cauldron and the sacrifice (neither of which I've done yet) make any difference? I'm really annoyed at the thought of having to quit so close to the end.
ADDENDUM - Because I'm a stubborn dunce, I just kept at it. I managed to cheese-sneak past the two Sentinels at Ukaizo, thanks to firecrackers and my 3 points in stealth. The fight with Furrante on my way back from the machine wasn't easy, but did it on my 2nd attempt (I switched to a greatsword with high damage -Whispers' is crap for single target-, chopped down the two priests asap, got lucky when a wizard cast a wall right in the middle of their group, and then went back to Whispers for finishing off the cattle), and I made it to the end of the game. It was fun, at times, and I don't mind a challenge but overall I feel I struggled more than I enjoyed this build.