I just ran this through Shard's build tool to see what I could see...and I saw a way to fix the saves:
- Drop the 2 Great Strength feats, and shuffle your Epic feats around to get Defensive Roll and Epic Dodge in Epic levels. - Take Legendary Fortitude and ESF: Discipline in LLs.
This will fix the one very real problem this build has: its fort save is abysmal. That fix alone will help. I would, however, seriously consider either Pharlan or Undying and going for 5Pal or 5Ftr instead of 4CoT/1Rng. Lemme see if I can come up with a build.
Ok, here's what I came up with, just on short notice, for Undying. It's STR-based, so it doesn't get all the nifty stuff like Epic Dodge and/or Self Conceal, but it should be able to deal a decent amount of damage and be able to tank acceptably. Be sure to ask for conceal from your friendly arcane/druid, and to wear mord/breach protection when needed. :-)
The ability scores in the final table are listed as naked. AB, AC and Saves assume just +12 gear. Add 1 AC, 1 AB, and 2 saves for +14 gear. Add 4 AC for the first demigod iteration, along with 1 AB and 2 saves. And another AC/AB and 2 saves at 2x (yes, this gets absolutely sick saves, but undying+pally/bg generally does). The skills are just copied from the original build, and haven't been updated to reflect the addition of Craft Weapon, which you should be able to afford by simply dropping some concentration (I'd take only 30ish), since Undying gets 60 extra skillpoints in LLs, and this build has +2 INT over the Wemic one. Skills fixed to match the new build. It no longer gets Spot, which might make finding traps a bit harder (not impossible), but it now gets Craft Armor, which improves the AC. You'll be short a few points, tho....take them from either Concentration or Pick Pocket.
For your artifact, I recommend the CON artifact if you have a Blind Fight pandect, or the DEX artifact otherwise. The STR arti might be nice, too, but is hard to get.
As an alternative, you could go with 5 levels of Fighter instead of Blackguard/Ranger, and perhaps even get PWF on this, for some amazing damage.
Here's another alternative I came up with. It results in a 20% XP penalty but it should have a -significant- offensive boost compared to the base build. Features dual bastard sword offense and enough STR to be a functional dex unitank.
AB(L60, +12s, no arty or demi): 16+10+12+7+26+3+20+2-2-1 = 93/88/83/78/95/93/88
AB is a bit lowish but with the extra attacks you should be able to manage. The 83 and 78 will likely not hit well but the offhand attacks should still hit reliably. Also double demi will get 3 AB (extra from opportunist), so this should be workable as long as you don't mind the XP Penalty.
Free feat can go to: Greater Weapon Focus, Toughness, Blind Fight, take your pick.
Right now until I can figure out what I can/can't do about all the picks I have already upgraded I won't be reincarnating this yet. I will have to check those numbers Arek but I am thinking some of them don't add up on your Undying and a STR version won't need ESF Discipline but might need it for Open Lock. I will have to check what armor works out with the DEX score you list becuase Opportunist and Crippling strike require you wear light armor or no armor.
Edit: Actually, no, Open Lock gets to 127 exactly at 60 with +14 dex and +50 from items/buffs/song (neither of which are hard to get at 60). Checking Discipline, you get 137 max naturally, so you're absolutely right - you don't need the ESF. Maybe take ESF: Listen there instead?
I am currently thinking I will drop the STR feats for DEX shuffle feats around to pick up Epic Dodge pre-LLs this just leaves the debatable Self Concealment feats. I will keep ESF: Search and dropping SF: Listen for SF: Disable Trap and dropping ESF: Disable Trap. I like the Self Concealment feats so I could look at dropping some Hide and dumping it into Pick Pocket would put it 2 shy of max ranks in PP which I could steal from UMD. I can use an LL feat to pick up L Fortitude. If I keep Hide maxed what feats might I be able to take in place of Self Concealment that would be worthwhile. The changes I am currently considering move the Self Concealment feats to general feats and to LL feats.
Unfortunately, I wasn't able to fit Slippery Mind on this. On the other hand, with Dim Maks you have 60+ Will anyway. If you really want Slippery Mind, you'll have to drop Self Conceal to get it. Just take another 4 great dex and Slippery Mind instead of the SC feats. You could even consider dropping just one SC feat for self-conceal roughly equivalent to displacement and take Slippery Mind that way.
Additionally, to get the 4 dex, this build drops blind-fight. Not a big problem if you use a dex arti, but if you don't, you could drop Toughness for Blind-fight (or SF: Search if you happen to have an Embroidered aug on something to swap in for searching).
Finally, to free up all the epic/legendary feats needed, this drops ESF: Search for SF: Search. If you have an Embroidered aug to stick on a ring, you can even drop that for blind-fight if you want. As for ESF: Search, you don't need it - SF: Search is enough at L60 with a +14 INT item (and GR in deeper areas - if you're having trouble getting GR'd when needed, just wear swap in a Belt of Eternal Preservation when you rest so that it's ready when you search, or use the PoM double-restore item).
Ok, since I obviously don't get it: Why Spot? You have to skip Craft Armor to get it, which loses you at least 2 AC (assuming you can hit 80 CA with gear/song, which is pretty easy).
Other than that, your new build is better, getting 96 AB and 132 AC with just +12 items and 80 CW (97/133 with +14s, 100/138 at single demi with +16 and +1 AB from being at least L64). I don't know that I'd take Epic Will, tho. Perhaps an Imp. Sneak feat would go better there, for a bit more damage, or ESF in Craft Armor if you take CA. :-)