Concerning Rangers, though not necessarily Blade Thirst... give them more feats. They're the dual-wield class, but they don't have the extra feats to support everything that they'll need to do it effectively. Either that or give them things like Two-Weapon Defense and ITWD automatically as they level.
I think this would require a lot of codeing, and likely a hak update. Not sure though.
The thing is that you would need to find the balance with these two bonus feats. On which level do they gain it? Since ranger is allready one of the classes, that most folks x-class. (Rogues mostly like them since a lot of free feats, i think at least 6 on first level, and the skill point loss is not that great, like when choosing a fighter.)
(Pure rangers are VERY rare, i think there are less than 10 pure ranger characters.)
Not to mention i have seen not one ranger use a double handed weapon, because it is easier and much more worth it to use.
Dual wielding if you walk along the path and reach the level of 9, will still be -2/-2 or -2/-4 and sadly that 10/20% miss chance is huge, on and above that level.
It is why most rangers use thw-s.(Not to mention that the damage output may equal or be higher than with dual wielding. More chances to hit with thd weapons *1.5 str bonus. And depending what weapon you use)
TWD and ITWD are those feats that are actualy the feats, you will most likely not want to waste a feat on.
As a ranger your saves will be fairly low. You will need to take all the feats that boost saves. The parry feats (both twd, thd and single weapon). Then thougness, since your constitution will be around 14 at best. That is allready at least 7 feats, and you were not even able to focus, or take up other favoured enemies.(You can switch out favoured enemy for other feats.)
Considering feats. A ranger gets if i made my math right 19-20 feats. A wizard gains 24. A fighter even more. Yes many say a fighter does not need that many feats, and i do not wish to debate about it, since i am not very well familiar with fighter builds. (But most cross class it usually.)
A ranger is supposed to be someone who can use stealth, can notice enemies and even know a few things about them, shoudl be able to calm animals, ask their aid, be a fairly decent "fighter" himself.
Sadly this is not the case here. They lack equipment, skill points, and feats to do so.
One thing though, an item for which i am really glad that was added to the loot table is the Axes of Hurling. They are meant for rangers, who have a semidecent str.
Blade thirst works on it, and you can rapidly throw the axes at your enemies dealing 2d6+3+str bonus+varnish. So if you play a ranger, take some str, and leave finesse alone, unless you can hoard up a serious amount of varnish, or can get a permanent cleric/caster friend to cast GMW on your weapons.
However...they weigh you down. Majorly. 50 of these axes is fifty pounds. Which will let you carry on your best days just that much.