Leaf armor and curved blade

[Menite Monk]

I guess I will start with leaf armor. It does not say it is made of Darkleaf Cloth and is 205g less then Darkleaf Cloth. Can you add Darkleaf cloth to leaf armor? do all the bonuses stack if you can like masterwork + masterwork?

Now the Elven Curved Blade. I do not have the core rule book yet so I cant see how it is written but the d20pfsrd sight has it written like this

Curve Blade, Elven

Essentially a longer version of a scimitar, but with a thinner blade, the elven curve blade is exceptionally rare.

Benefit: You receive a +2 circumstance bonus to your Combat Maneuver Defense whenever a foe attempts to sunder your elven curve blade due to its flexible metal.

You can use the Weapon Finesse feat to apply your Dexterity modifier instead of your Strength modifier to attack rolls with an elven curve blade sized for you, even though it
isn't a light weapon.

Weapon Feature(s): finesse

what is this weapon feature at the bottom??? does that mean weapons Finesse comes built into the blade?

And next would be how would one go about adding

Sacred +++++

A sacred weapon is filled with divine energy, and acts as a holy symbol. When wielded by a creature that can cast divine spells, the weapon automatically displays an image of
that creature's holy symbol, often as a glowing rune on the weapon's blade or along its haft.

Additionally, if the wielder has the blessings class feature, whenever he channels energy, he can choose one ally or ally's weapon within the area of the channeled energy and
bestow upon that creature or weapon the benefits of one of his minor blessings at a cost of one use of that blessing.

It has no gp Cost just - Cost +1 bonus; Feats Craft Magic Arms and Armor; Spells imbue with spell ability.

[Bob Bob Bob]

Leaf Armor cannot be made of Darkleaf Cloth because "Items not primarily constructed of leather, fur, or hide are not meaningfully affected by being partially made of darkleaf cloth." Leaves are not leather, fur, or hide.

Same bonuses never stack with themself (to the best of my knowledge, is there a corner case I'm missing here?) so masterwork would never stack with masterwork.

The Weapon Feature(s): finesse just means you can use the weapon with Weapon Finesse despite it not normally being of the right type. You'll notice that the rapier and whip also have the "finesse" feature. Weapon Finesse normally only works with light weapons, weapons with "finesse" are exceptions to that rule.

You already listed the cost of a sacred weapon, "+1 bonus". This means it's equivalent to a +1 bonus. On a +1 weapon it would only cost 6,000 gp to add Sacred to it (making the weapon a +1 Sacred weapon, or +2 equivalent). On a +5 weapon it would cost 22,000 (+5 Sacred being a +6 equivalent weapon). You pay the difference between what the weapon is currently and what the weapon will become. +1 to +2 takes 6,000 (8,000-2,000), +5 to +6 takes 22,000 (72,000-50,000). It must be at least a +1 weapon first so it costs at least 6,000 (+1 to +1 Sacred) and at most 38,000 (+5 Holy Flaming Frost to +5 Holy Flaming Frost Sacred). Half that if you craft it yourself, as always.

[Thanael]

Weapon Feature(s): finesse

means this weapon is eligible for use with the weapon finesse feat. (It's "finessable") You still have to get the feat though.

It's a Special Weapon Feature like brace, or double. See under Special Weapon Feature here

[Menite Monk]

Thank You so much that's exactly what I needed to know.