My Brute has Mace Mastery. I took Web Envelope, Disruptor Blast and Summon Blaster. All 3 are still in my build, but only because I wanted the pet.
WE is good for holding foes (but not very important for a melee AT). Long redraw and recharge times though!
DB has good targeted dmg (but needs to be 3 or 4 slotted as a minimum). Definitely needs to have at least 1 acc IO in it. But has long redraw and recharge issues like WE.
SB is good for standard mobs, but they get killed quite quickly against EB/AVs.
Mace should work well with SoA spiders, but redraw may put you off.
If I could change my patron, I would in the blinking of an eye.
Main 50 & Badger Nine Claws Claws/Regen/Body
Other 50's Ph10x Brute Unjust Law Tanker Samantha Urai Scrapper Codename 1250 Scrapper
Cepheus Defender Nilus Scrapper Electro Field Blaster S.PONGE Tanker
Mace Mastery is useful if you think you might respec into a Bane at some point.
Otherwise, the most intresting PPP for a crab is Leviathan Mastery, since Bile Spray benefits from the -40% tox resist in Venom Grenade.
I really should do something about this signature.
Now I think why I decided on the Webmaster getting Web Envelope, and not Wide Area Web Grenade, was it down to redraw, recharge, accuracy and aoe?...Looks good..
But it fails on most anything else because WAWG does everything else better, ie the -rechg, -spd, and prevents all forms of knocking about....but by taking web envelope so damn late instead of WAWG the intention in need could well be different and more specific...*raises eyebrow*
So is WAWG better than Web Envelope?
..yes and no 
but the idea of 6 pets sounds fun to me.
He will honor his words; he will definitely carry out his actions. What he promises he will fulfill. He does not care about his bodily self, putting his life and death aside to come forward for another's troubled besiegement. He does not boast about his ability, or shamelessly extol his own virtues. - Sima Qian.
Well the stats on Mids for both:
WAWG/Web Envelope
End - 7.28 / 12.7
Rch - 30 / 20
range - 80 / 80
Cast - 1.87 / 2
Radius - 10 / 15
Duration - 20.1 / 20.1
So the WE is more end heavy, but has a slightly wider radius, and quicker recharge time with only a slightly longer cast time.
I just find the idea of using Bile Spray a bit..well...un- thematic. The idea of having an extra spider does appeal though, just for entertainment value, which is what its all about. This is a toon used for an all SoA team after all, not much stands up for long as it is, which is why im not that fussed about getting WAWG. Also, I'm not really intending to take any of the melee attacks, at least not yet, thats what the widows on the team are for 
My question is, what do you want it for?
For debuffing mainly a high ranked ST + maybe more then go WAWG.
For mainly a power pick for another pet then go WE.
If thats all the stats your interested in then go for WE and get the pet.
He will honor his words; he will definitely carry out his actions. What he promises he will fulfill. He does not care about his bodily self, putting his life and death aside to come forward for another's troubled besiegement. He does not boast about his ability, or shamelessly extol his own virtues. - Sima Qian.
Scuttle forth my spidery minions and go blast the **** out of stuff
WE it is then
I was looking at a Crab Spider build for my SG all SoA team so I'm buildling him slightly different to how I would normally. I thought it would be a lot of fun to get the pets, stay at range blasting and lobbing grenades. I then saw for Black Scorpion patron (who else could you have for a Crab?), you get more mace blasts, a web grenade that while heavier on end looks better than the WAWG, and a Boss level pet, giving me the same amount of pets as an MM.
So I'de like to know some views, are the patron powers worth it if I can fit them in? Would 6 pets be overkill? Is the Web envelope actually better than the WAWG?
Thoughts please