Armamentalists are warriors who rely on the small magic ability within them to propel their martial skill.  Armamentalists are warriors who either chose to master their magic differently than an Eldritch knight or found that their arcane ability was strong but limited.  They learn through practice and experimentation how to adapt their equipment to their current needs, and in battle they are well regarded for this ability.

Observe, Analyze, Project

At 3rd level you gain the ability to magically create a copy of nonmagical weapons and armors you are proficient with.  As a bonus action you expend a 1st level or higher spell slot to bring into reality a single weapon or full set of armor, materializing the object either in your hand or on your person fully equipped.  Each projection you make suffers a -1 to attack and damage rolls (if a weapon) and a -1 to effective AC (if an armor or shield).  You can improve the durability and effectiveness of your projection by spending a higher level spell slot, granting the weapon or armor a +1 bonus for each spell slot level above 1st that you use to conjure it. 

Any projections made disappear after a number of minutes equal to 1 + your Int modifier, any projections you made can be dispelled early as a bonus actions, and when you create these projections you can choose to equip them yourself as part of the bonus action or equip them to any willing creature within 30 ft of you.

Improved Projection

At 7th level your projection abilities improve with your experience.  Your weapons and armor now count as magical for the purposes of overcoming resistance and immunity to nonmagical damage and for effects that only work against nonmagical armors.  Your projections no longer have a -1 penalty to their attack rolls, damage rolls, and AC.  Additionally, you can inspect a weapon or armor for 10 minutes and learn the properties of that piece of equipment as if you had cast the Identify spell on it.

Reformatting

At 10th level you can cast the shield spell a number of times per long rest equal to your Intelligence modifier.  You also gain the ability to use your power to alter magical items for a time.  Using a bonus action and a 2nd level spell slot, you can alter the form of any magic weapon or armor you are touching to a different armor or weapon type for the same duration your normal projections last.  At the end of this duration the magic item returns to its original form. For example, a flame tongue longsword can be turned into a flame tongue glaive or greataxe, but when the time expires the weapon reverts to its original longsword form, or a set of scale mail of acid resistance can be turned into a set of plate mail of acid resistance, but returns to being scale mail when the duration expires.  Magic items that require attunement resist this effect entirely unless they are attuned to you.

Reinforcement

At 15th level when you use your Second Wind feature you can choose up to 3 creatures within 60 feet of you.  You and the creatures chosen gain a bonus to AC equal to your CON modifier until the start of your next turn.

Unleashed Armory

At 18th level you have learned to project and manipulate your projections.  Once per long rest you can summon a number of weapons equal to your intelligence modifier anywhere within 60 ft of you.  These weapons all operate as a Spiritual Weapon spell cast at 3rd level, and you can use the same bonus action to direct all of them independently.  Your spellcasting ability is Intelligence.