Your patron is an arcane being of great power, whether its a wizard of great renown, a particularly studied sorcerer or a litch whom doesn't want to bestow upon you power over the dead, however they expect you to put in the work to learn your magic, with some assistance of course.

Gain access to the wizard spell list, the ability to copy and use unknown spells using arcana and a spell book that works like a wizard spell book. In essence its a wizard warlock.

Nerdlock if you will.

Eldritch Study

At 1st level you learn any 3 cantrips from the wizard, sorcerer or bard spell list. They count as warlock cantrips to you, but they don’t count against the number of cantrips you know.

Additionally you gain proficiency in arcana

Arcane Spells

The magic and teaching of your patron allows you a diversity of magic unrivalled by even the most skilled warlocks. At each specified warlock you may pick a number of wizard spells. These spells are always prepared.

Fiend Spells

Warlock Level	Spell Levels
3	1st level spells (2), 2nd level spells (2)
5	3rd level spells (2)
7	4th level spells (2)
9	5th level spells (2)

Eldritch Knowledge

Turns out, access to the knowledge of a powerful arcane being can be pretty useful. You may use Charisma instead of Intelligence for any intelligence check, you also gain expertise with arcana.

Quick Ritual

You may borrow some power from your patron temporarily. You can cast a Ritual spell that you have prepared using an action rather than the extended time for a ritual. Doing so does not expend a spell slot.

You can use this feature no more than once per Short Rest.

Arcane Skill

Your connection to the weave is deepening. You may use 'Arcane flare' this allows you to cast a single spell without expending a spell slot. This feature may be used one time per Short or Long Rest.

Favourite Spell

You have studied all of this time, now its time to graduate. You may pick any 1st or 2nd level spell from the wizard or warlock spell list, you may cast that spell without expending a spell slot, additionally if that spell was written in your spell book it no longer requires an arcana check to cast.