For 2 slots and a chunk of change you can get +3.13 ranged/AoE. Just throw all three Blessing of the Zephyr's in your travel power.
In Mids, go to Options->Advanced->Database Editor.
In the new window, click on the Main Database Editor.
In the new window, in the left-most column, choose "Tanker_Defense."
In the middle column, now choose Shield_Defense.
In the rightmost column, choose Phalanx_Fighting
Below the rightmost column, hit the Edit button.
Yet another new window! Here you can change a lot of things - but what you want is the Power Scaling component (It stands out with orange boxes on mine.) You are going to want to tell it that the slider should go from 0 to 3 instead of from 1 to 3. Then save you changes, and leave (saving at every window, of course.)
Now Phalanx for a Tanker will scale from 0 allies in range, letting you see the effects the power has when solo.
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are you able to 6 slot build up?...cause you can also get 2.5% melee,2.5% aoe a,d 2.5% range defense in the 6th bonus
plus you can get the steadfast 3% defense unqiue which is relatively cheap nowadays to help all your defense types
hopefully your using weave and cj as well in your build..if you post the build i could help ya more since my shield/fire is soft capped
i did however get the other 3% defense from the new pvp i.o's but thats alittle too much to ask atm with pvp recipes broken
With just your shield defense powers, weave, combat jumping and the 3% steadfast IO you can get 42% defense. Getting the last 3% to soft cap is up to you.
For True Grit you want to maximize the +hp you get out of it, so throwing uniques in it is not a good idea. Throw all 3 uniques in health and then a numina and miracle heal plus a common heal IO. Then in True Grit use 1 common heal and 2 numina piececs with 3 titanium coatings.
I am an ebil markeeter and will steal your moneiz ...correction stole your moneiz. I support keeping the poor down because it is impossible to make moneiz in this game.
For my Shield /Mace tank I have at least 47% defense to all positions, and I don't have weave or combat jumping. I used all set IO's and don't seem to have sacrificed anything at all to get there.
I am now lvl 50 and can take out 2 Mobs of Cimmoraeons on the Wall in about 5 seconds without being touched while I herd usually. I use a mix of Touch of Death, and Mako's in my single target attacks, and then a mix of Scricco's Devs and Oblits in my AoEs.
I use the melee and PBAoEs to shore up my Melee and AoE defense. I use Red Fortunes in my shield toggles to get ranged defense from the 6 slot. I also added Manuvers also six slotted for another place to put a red fortune and found it atually really helped boost my total defense while still allowing my winged character to be able to take the Flight pool.
In the flight Pool I took 2 slots each in hover and fly and used Blessing of Zepyer's for more ranged defense.
Lastly I took Build Up and six slotted it with Gaussin's Fire Control and got a huge defense buff to all three positions 
The only thing that can reliably hit me now is an AV it seems and those can only really hurt me if the are 50+ lvl 50 AVs I can afk against them, and I have afked right next to a Rikit Pylon in RWZ and came back and she was alive still after 10 minutes hehe. I love my tank and have spent a bunch on here to get all the best sets, but i don't need an purples (though i've been seriously tempted to start saving for a set for Clobber, but it would just hurt my defense lol.
Well, if you've got a spare slot and about 600 million inf, you could go for one of those Gladiator +3% defense IOs.
Also, do you have a Steadfast Protection +3% defense slotted already? If not, that'd probably be BUTTLOADS cheaper.
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OK, thanks folks, it looks like I got a few things answered. I'd still like to hear someone chime in re: Defense Debuff Resistance, but I can figure out what works and what doesn't once I get a few more levels on me.
Thanks again.
I can help you with defense debuff resistance based on what I've read here. IIRC, the best way to get this higher is to stick two Hami-Os (Membranes I think? whichever is rech/defense) into Active Defense. Due to a miraculous glitch (or feature?) the defense buff actually boosts your debuff resistance. This should also free up a slot for something else, since it seemed to me like your starved for those 
You want three slots in AD for the Hamio trick.
Yep, three slots is the sweet spot. Remember you want as much recharge on Active Defense as possible as well so that it double stacks.
That with your regular defensive slotting on Battle Agility will do the trick.
Hey folks. I'm planning out the build for my first serious attempt at a Tanker, a Shields/Fire. I think I've got it sussed out pretty well, but I do have two key questions.
1. Phalanx Fighting: I'm trying to figure out how this reports in Mids. It looks like the best thing to do is "toggle" it off in Mids, and just add 5% to each of the positional defense values, since there is no way to set the slider for it to 0 teammates. Is that the trick?
2. Heal IO Set Uniques: I'm looking to pick up the Numina's, Miracle, and Regenerative Tissue Uniques. Right now, I've got them (in Mids) slotted as follows: 2 Miracles in Health (the Unique and the Heal), and the Regenerative Tissue Unique, along with 2 Numina's (the Unique and the Heal) in True Grit. The question is, mathematically, is that the best way to maximize +HP and +Regen?
Thanks in advance for any tips, advice, etc.
P.S.: Oh...I'm having a hard time getting everything I want, and still Soft Capping my AoE Defense. Right now, with no teammates in range, it's sitting at 42% (44.5% if I toggle on Hover; yes, Hover, no CJ--that's a sacrifice I had to make for character concept). For the folks with high-end Shields/general Defense experience, should I be all right with that level of Defense against AoE attacks?
P.P.S. Aaaand...what is the general consensus on an acceptable level of Defense Debuff Resistance? Right now I'm sitting on 56.2%, but that spikes to 77.8% for decent periods of time (due to 3 Rech IOs, Hasten, and Global Recharge causing Active Defense to double stack)
OK, I think that does it this time.