I guess the main reason to have 40 cards were the hourglasses. With a 30 card deck, there's little reason to have hourglasses, since you have to stop drawing extra cards quite early. Whether due to already being at 0 cards and having to rewind your scarabs, or due to being at ~10 cards left against an opponent who can blow up your Eternity.
With 40 cards you can add a few hourglasses and still have some fun drawing cards before you have to stop. And, even if opponent blows up your Eternity before destroying your Hourglasses, at least he destroys Hourglasses before shields/SoGs, so generally a 40 card build with hourglasses should be better against decks with some PC than a 30 card deck without Hourglasses.
In other words, it entirely depends on your opponents. I didn't design Pharaohs Gratitude with a particular AI level in mind. I designed it because some-trials-long-ago required me to design a unique mono deck. And I designed it with mostly fun in mind, so I tried it against both AI3, top50, AI5 and FGs. And I tweaked it with all these in mind, so that the deck would even stand a chance against some FGs.
Of course if you plan on using the deck against eg. AI3, you can drop Hourglasses and some defenses and make it a 30 card deck. Against AI5 you could drop Hourglasses and make it a bit smaller, like the 33/34 cards you suggested. They rarely have PC anyway. I don't really remember how it worked against top50, but that environment changes quite often, so you have to make other tweaks depending on these changes.
As for the Animate Weapon, it is a great addition. Indeed, if this deck wasn't required to be mono, one Animate Weapon would probably be there. Though, on the other hand, in my
half-Time half-rainbow anti-FG deck (
http://elementscommunity.org/forum/index.php/topic,4958.0.html) I'm not using AW because it is too often a dead draw. It's only useful in late game, while I would need more defensive cards early. And most FGs have enough CC to kill a flying Eternity unless it is quinted anyway. Against AI5 you have more Time to set up, so it's different.