I go along with Azred on having your tanks avoid damage first - never mind HoF, it's necessary on Insane. Sometimes you just can't dish out the hurt fast enough to avoid getting killed.
My 'mental picture' example of this was when I mixed it up with Ilmadia's fire giants in Lower Dorn's. I was standing on one of the islands, fully buffed, with nasty spells out front, elemental summons, the whole shebang. My elementals lasted about 30 seconds, my paladin tank lasted a couple of rounds with Lathander's Shield, then got hit hard by Ilmadia - this is with about -20 AC and bardsong, mind you. I had to retreat two islands, rotating my tanks. When it was all over, no character except the non-combatant bard had more than 10% of its hitpoints, and I had a mere half-dozen spells uncast out of a full repertoire (4 casters + paladin). All my characters wouldn't have survived, except that my bard's last spell, Flesh to Stone, luckily took down a healthy Priest-Mage of Vhaeraun.
You have to have shields. When each enemy hit costs 20+ HP, it's very important to make them miss as much as possible. You do not want to get caught in a battle of attrition with tough, numerous, hard-hitting foes. You will lose. Strategy, spells, and equipment are what enables a party to take on enemies, not sheer HP. On higher difficulty levels, I typically have the first two tanks using shields. Any rangers or characters using two-handed weapons enter combat from the secondary position, limiting their exposure to attacks. Of course, with a bard, you can rotate your tanks and it doesn't matter if one tank tends to take damage faster; you just have to rotate it sooner.
Re: 5 PP in weapons - I kind of like doing that. I so rarely take single-classed fighters that 5 PP is a novelty for me. Whenever I get it, it's usually in Axe. It's melee and ranged weapon for the price of one. That frees up more PP to take 3 or so in a bludgeoning weapon. You can still use axes with shields, just not the two-handed ones. I'm not a big fan of any of the two-handers anyway - the Celebrant's Blade is good enough for me.
Re: a durable fighter build with two-handed weapons. Why not a Fighter/Mage? Mirror Images and Stoneskin make pretty good shields.
I will admit to using Joril's Axe with a Fighter[13]/Mage with 5 PP in Axe. Mirror Image takes the pain, Stoneskin blocks enemies long enough to cast another MI, and repeat. Makes a very durable tank, as long as you have enough of the right spells.