I see well thank you verymuch. I plan on adding a synergy chapter when I get around to that too.

as of the athene's update now giving it ap I wouldn't upgrade it first. the mana to hp regen is far stronger early when you can get a censer or redemption and keep it chalice while you need more sustain and move on to ap when everyone is tankier and can cover for that.

Athene's Unholy Grail is more burst healing and better for a general team comp. unless I'm with at least two carries that can use a flat heal and damage, say a yi jungle and lucian bot I won't sometimes bother with Ardent Censer when a Redemption can do its job as well as having an aoe heal. Ardent Censer is a bit situational like that.

for Forbidden Idol vs Aether Wisp sure you'll have a bit more shield early but the 10% quickly catches up in the midgame and the idol gives not only the shield but a boost to cdr and mana regen meaning you can not only have a comparable shield but have it up more often and have mana left over for other things. the whole dealio around my early build is lots of sustain so you can keep spamming and relying on base damages to hopefully carry you through to late. Forbidden Idol simply gives more in mixed stats which in my personal opinion is the hallmark of a strong early item. I remember when censer was first changed to the "+100% of whatever is lower of hp or mana" and it was the most broken item to rush early game and just never go back to base until you had enough gold for 3 more items. now it's pretty good early but needs other mregen items to scale off of, and now it's as good as if not better than it was before in the mid to lategame what with redemption adding 125% mana regen for a grand total of healing like a mundo with a warmongs. even if you aren't getting athene's because you need a cc cleanse for the other chalice upgrade I'd almost say a chalice item is a must every game.

the nerfs were kind of weird, I don't quite understand their purpose. I do know e max lulu will phase out of being utterly ubiquitous slowly and she'll be less safe of a pick than she was before. of course with every nerf riot tries out it invariably hits support lulu more than it will solo lulu if it hits her solo lane at all.

vs blitz can be done. but it is one of the more dangerous matchups in my experiences not only because you could get hooked but your ally could as well, and vs aggro lanes that can spell out your deaths if you can't react fast enough. basically constant vigilance and care and it should be fine, but any aggression you show can be turned right on you by the blitzcrank if he knows a lick of what he's doing. karma does truly **** on him though, nice choice.

as for skins? I haven't like rigorously tested them or anything but all I picked pool party lulu for was her shield being a shade of aqua to be very visible to allies as well as having a great overall aesthetic that you can't really go wrong with if you can only buy one lulu skin.

further thoughts on the nerfs, 240 seemed to be the gold standard for shields in the game, but when you think about it that's like half an auto attack late game unless combo'd on top of other shields or heals, what you really got them for was the burst resistance and the actives that could come along with it such as movement speed or some form of damage or resists. the shield will still be good on a kog'maw with a censer and runan's as it was intended but it won't be such a good protection tool early. I've always said lulu shouldn't be locked into the whole LOCKET REDEMPTION OTHER ITEMS build that's dominating the support scene these days. I wish she had some good to okay utility bases that scaled well with ap (not the damage, mind you) so she could build ap and scale up with the hypercarries she protects. it's not outrageous when you think about it, rakan comes out with a 90% personal shield and a total of 230% in heal and shield scalings with an 80% ap shield (double cast mind you) so why not try out a 130 max base shield and really good scalings on her ap. it would certainly be fun spamming around 600+ shields lategame I tell you what.
oh and to actually answer the question the only reason I'd get a third point in q while maxing e would be to scare off aggressive carries, but at the same time you really need that shield so it's a trade off.

she is extremely good at shutting down at assassins especially with a locket on hand. imagine you're a zed who just ult ignited on the adc and suddenly you're knocked up, they're massive, have an entire 700ish health more than they originally did, plus a 300 shield plus the 1k shield from locket and should you manage to get through any of that you're now unable to do anything for a full 2.5 seconds other than walk around slightly.
lulu is unique in that she does not care about ignite, similar to how yi doesn't care about exhaust. her ult's heal cannot be stopped by an ignite and her low cooldown shield certainly doesnt, 5.5 cd for a 6 second shield max rank. that and her very low lategame cooldowns because all her builds fill her up on cdr quite easily (in fact often I get too much cdr but I learn not to care about that so much) lategame her 80% slow for 2 seconds is on a 4.2-3.8 second cooldown.

the best time to kill anyone on her team is in the small time when one of your bruisers or tanks has just initiated and her cooldowns are down, bonus points if It's a tanky bruiser like kled or renekton that she really needs to focus in order to stop them from one shotting any squishies, at that point all she can really do is shield when it comes back up.

should this fail it's actually a good tactic to focus the lulu down if she even misplaces slightly, make her panic and force her to ult herself and she can't use it on the adc. most novice or even moderately experienced lulus will ult themselves to try to stay alive, and only the most masochistic ones will sacrifice themselves for their carries.