Yes, you should splash 20 levels of fighter Any other melee class that isnt ranger (yes, even paladin is better at TWF then ranger atm with equivalent gear). Better mileage from your class features.
Ranger hasn't been well treated well in a long time in ddo
......Ranger, on the other hand, hasnt gotten anything new since they rewrote AA, besides a few spells they cant use from druid
1: There are more then 6 types of enemies you will be facing in epic.
1a: Shirardi is **** for making your one class feature slightly more flexible
2: Getting 3 of your feats for free doesnt matter too significantly when they are replaced by a worse feat tax
3: Critical modifier is expanded and enhanced by Kensai, while the capstone is the same as all the benefits of Tempest 3. Kensai also has a boost that gives +6 strength, as well as having pre-requisites that match the effectiveness of Favored Enemy at every level
4: Shirardi is absolute hell for anyone who does a tempest ranger.
5: No strong class features exist within ranger, except for their ability to prepare FoM and Camoflage
6: Evasion + a small boost in AC is not an Epic Cavalry Plate T3, Favored Enemy is not Kensai, Sneak attack (which can be landed 60% on Undead/Constructs in class), Frenzied Mighty Rage, or Exaulted Smite Evil 4. You dont have Improved Sunder or Devastating Critical.
Let me put it this way: If i say a class sucks, i have a good reason for believing it does.