Don't rely too heavily on blackguard. Past level 2 they are a weak class. A d10 hp really doesn't matter at all when all your HD turn to d12.
As a character with no Con bonus to hp and 5 fewer HD than expected, you won't be the tank at epic levels, regardless of what you try. If you can, convince the DM to let you take a feat to use your Cha for bonus hp instead of Con, but I don't remember where that's from.
At epic levels, with sucky hp, a tank is a lump of tasty tasty tofu waiting to be devoured by the first thing that comes along. It will suck and you will hate it, and you can't get ressed.
If you already have multiple arcane casters, make them summon you some tanks. Heck, just make them tank. They'll almost certainly have more hp then you do.
I suggest a different take on Death Knight.
"Unstoppable Death": Rog 1/Monk 4/Lurking Terror 3/Blackguard 2/Assassin 7
For a really tormented build, try "Deathless Pariah": Rog 3/Monk 4/Ur-Priest 10
For items, you really want something with a constant Anti-Life Shell. 132k, and it will save your bacon. Also consider something that can cast harm, to heal you.
If you really, really want to play a tank, I can only think of one good way to overcome your wretched hp...
"Deathless frenzy, redux": Barbarian 6/Blackguard 2/Frenzied Berserker 9, because, really, nothing says "Death Knight" like a 400 hp scythe critical.
As a character with no Con bonus to hp and 5 fewer HD than expected, you won't be the tank at epic levels, regardless of what you try. If you can, convince the DM to let you take a feat to use your Cha for bonus hp instead of Con, but I don't remember where that's from.
At epic levels, with sucky hp, a tank is a lump of tasty tasty tofu waiting to be devoured by the first thing that comes along. It will suck and you will hate it, and you can't get ressed.
If you already have multiple arcane casters, make them summon you some tanks. Heck, just make them tank. They'll almost certainly have more hp then you do.
I suggest a different take on Death Knight.
"Unstoppable Death": Rog 1/Monk 4/Lurking Terror 3/Blackguard 2/Assassin 7
For a really tormented build, try "Deathless Pariah": Rog 3/Monk 4/Ur-Priest 10
For items, you really want something with a constant Anti-Life Shell. 132k, and it will save your bacon. Also consider something that can cast harm, to heal you.
If you really, really want to play a tank, I can only think of one good way to overcome your wretched hp...
"Deathless frenzy, redux": Barbarian 6/Blackguard 2/Frenzied Berserker 9, because, really, nothing says "Death Knight" like a 400 hp scythe critical.