I also wouldn't call Chakra an exclusive weakness either. Sentinel's Chakra abilities dominate Shadow Walkers as well.
Using Chakra DPS spec on a Shadow Walker is not smart :p
Shadow Walker has one of the highest Chakra protection of all classes so using a Chakra Spec on a Shadow walker so will the Sentinel lose.
Defender in the other hand has Insane high physical protection, BUT
they have 0 Chakra protect.
The only protection they have against Chakra is a buff that last for around 5 seconds, which doesn't help mutch.
So all your chakra abilites will do 100-90% damage on him while the physical will only do 30-20%
Shadow Walker has 2 Abilites that has very high Chakra damage so you should be able to kill a Defender with 3.5k HP if i can kill him with a Hybrid spec Sentinel.
Remember that you must have high Eva, HP, Chakra DMG and Crit if you are going to make a anti-tank spec.
but this guide only works at low level, you won't be able to solo them at lvl 40+, you will need at least 2-3 players to take down a Defender.
Where do you get this idea that SW has a high CH defense? We have CH-EVA skills that can only be used 1/3 of the time. There's no actual "resistance" skill. And atm I have 580 Resistance to Voltage 80 to Gravity, and 200 to particle from trinkets, but sentinels still hit me hard on Chakra attacks.
Shadow Walker only has one skill that deviates from average Chakra damage btw: Shadow Dance. Every other skill I have list CH ATK at 134-180. Shadow Dance 404- 548.
As for gear:
I don't know about you, but I don't think there's exactly too many ways to improve upon it at this time. I do have Bangles with both min and Max CH attack, which would be more offensive than these ones. I also have gloves that have Crit, Defense, and CH-ACC, but again, it's not a huge difference.
There are defenders even medics, who can survive this gear atm, without even having half as good gear. And it's not that I don't know how to play either; I can PVE team bosses almost solo. Until School started up this week, I was also ranked #7 overall pvper on our server. Now I've fallen to 16. Point is, I doubt it's nubness, and it's certainly not gear. But I feel like SW has plateau'd atm, and unless I have 8 enhances versus other people's 6-7, I seem to be getting consistently beaten by classes that shouldn't be able to do that consistently. (I don't care about losing sometimes, but when you lose all the time to those classes....)