Dark knight: Am I failing or what!?

Just wanted t point out that 4.9k hp is a lot more than most ranged chars have at skeles

Irrelevant comparison is irrelevant. I seriously have heard more than enough of ranged people ranting about their fragility.
Also, being a Dk at HT pretty much is all about an upgraded Hbmule. That much is universal.

When I started out Zerking (around lvl125 with original Zerk skilltables), I died 20 times a day at Wolf Spiders, but I fail so let's skip that. Your problem here is Zerk lvl, get it to 30 and you'll be good to go, your dmg range is fine.

 Spoiler

The point is you don't need more than 7k~8k HP for Zerk. Of course you can't zerk HT or Tengu or Anego (no one can tank her anyway) but you're not missing out on any more fun. Besides, fun is where the challenge is.

As for Oblivion (Time Piece hunting), you might want to consider some more HP for room 3/4, as for 1/2, you can zerk slowly but safely with some strategic fighting.

It's better that you max Berserk, grind to 14x or higher and start joining HT for whatever other reason. No one would want a 12x hbmule that very likely could die in 2 magic attacks. Then again, joining HT is all about connections..
EDIT: Maybe borrow some money to get zerk30, grind to appropriate lvl and HT, pay back with your payment. Expecting to upgrade your Zerk30 through HT runs is not very... realistic.
Again, it relies on your connections with HT hosts.