School of Arcanology

Every wizard knows that the origin of magic comes from the Weave, the body of Mystra, the fabric of energy which all energy comes from. Normally wizards stratify, studying different aspects or components of the Weave, but not the arcanist. The arcanist studies the weave in its entirety, in its purest unadulterated form, and through that knowledge discovers secrets beyond the the realm of wizardry.

Mystic Scholar

At 2nd level your study of the Weave has increased your aptitude as a wizard and gives you adept insight on arcane knowledge.

The Amount of spells you have prepared increases by your proficiency bonus and increases incrementally with it as well.

Additionally you gain proficiency on Intelligence (Arcana) checks if you don't already.  If you are already proficient in the skill, you add double your proficiency bonus to checks you make with it.

Arcane Mimincry

Starting at 6th level, you have become proficient in deducing the intrinsic nuances of magic and the arcane, giving you the ability to reproduce spells merely by observing the casting ritual.

When you see a spell being cast of a level you have spell slots for you can choose to make an Arcana Skill Check with a DC of 12 + the level of the spell being cast. On a success you can memorize the spell. You can cast this memorized spell as if it were a Wizard spell, using you slot level, spell save DC, spell attack bonus, and spellcasting ability modifier. 

If a wizard can learn the memorized spell you can attempt to decipher it. Spending the appropriate gold and time for the base level of the spell. You can add it to your spellbook. The spell must be memorized throughout this entire process, and if it is lost you may not add it to your spellbook and lose the gold spent researching it.

You may only memorize one spell at a time, attempting to memorize another erases the first. After you cast a memorized spell it is lost to the recesses of your mind and you may not memorize another until you complete a long rest.

Whispers of the Weave

At 10th level, you have a revelation into the nature of the Weave which leads to magical discoveries of untold proportions.

Instead of picking two wizard spells, you may choose four spells from any class and add them to your spellbook. A spell you choose must be of a level you can cast, as shown on the Wizard table, or a cantrip. The chosen spells count as Wizard spells for you and are considered to be always prepared.

Archmage

By 14th level, your long and arduous studies have granted you mastery over the Weave. With your knowledge you can cast magic at even greater proficiency and as such spell cast with the Arcane Mimicry feature gain the following benefits.

• You may add your proficiency bonus to your roll when making a concentration saving throw.
• The damage or healing dice is increased by your proficiency bonus.
• If a spell forces a saving throw you may impose disadvantage for one target within range.
• You can now cast the Arcane Mimicry feature three times per long rest.

Additionally, you may cast any spell you have prepared through the Arcane Mimicry feature to receive the previous benefits.