As a master in utilizing versatility in the battlefield, those who master the way of the arms use various weapons against their opponents. The ones who follow the way of the arms usually are the masters of the battlefield rather than the academic fields but many are proficient in other subjects such as arts and crafts to increase their versatility. 

Versatile Knowledge

At 3rd level, you gain proficiency in Athletics.

Quick Hands

You can switch to your other weapons as a free action on your turn.

Weapon Arsenal

When you choose this archetype at 3rd level, you gain three weapon masteries for weapons of your choice.

Weapon Masteries

Greataxe: Whenever you deal damage a creature with your greataxe, you can open a deep wound on them. As you deal damage, you can choose to inflict a wound on that creature. At the start of their next turn they take 1d4 piercing damage. This effect can stack up to two times per creature. You can use this ability a number of times equal to your proficiency until you finish a long rest.

As an action, you can choose to cleave your greataxe in front of you. You make a melee attack up to two creatures that you can see within range dealing 1d8 slashing damage on hit. If you hit at least two creatures with this attack, you can inflict a wound without expanding any points. You can use this ability once until you finish a short or a long rest.
Greatsword: As an action, you can choose to cleave your greatsword in front of you. You make a melee attack up to three creatures that you can see within range dealing 2d4 slashing damage on hit. If you hit at least three creatures with this attack, you can make an attack as a bonus action to the nearest creature.

Your greatsword gains reach, if you are not in 5ft of range of a creature your attacks deal 2d4 piercing damage.

Glaive: As an action you can make a flurry of attacks. You make 1d6 attacks with disadvantage against a creature within reach. Whenever you take this action, make a DC 13 Constitution Saving throw. If you fail, you either choose to gain a level of exhaustion or skip your next turn. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

You reach increases by 5ft while wielding a glaive.

Heavy Crossbow: As an action, you can make a pinning attack to a creature's legs. That creature makes a Strength Saving throw against your attack, if it fails that creature is pinned to the ground and has 0 moving speed until the start of your next turn. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

As a part of your attack action with a ranged weapon you can also reload.

Longbow: As a part of your attack action, you can choose to draw two additional arrows from your quiver. Your next attack with three arrows is with disadvantage and deals three times the damage dice it would normally do. If you make a critical hit, your damage dice is doubled as it would normally do then the extra damage dice is added to the damage roll. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

Your ranged attacks with longbow within 5ft of range is not with disadvantage.
Longsword: As an action, you can choose to take a defensive stance. While in this defensive stance, attacks against you are made with disadvantage. If a creature hits you while you are on your defensive stance, you can make a counter attack with disadvantage against that creature. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

Your first attack with longswords on your turn are always with advantage.
Rapier: As a bonus action, you can declare a duel to a creature using a martial weapon. When in duel, if no creature is near 5ft of you or your opponent you deal an extra on 1d6 and your opponent deal 1d4 more damage to the other one. If the creature is not using a martial weapon, your damage is decreased to 1d4 and your opponent deals no extra damage.

After each attack with a rapier, you can move up to 5ft to an unoccupied space you can see. This movement can triggers opportunity attacks.
Shortsword: As a part of your attack action, you can try to disarm your opponent after a successful hit. If you choose to not hit but successfully disarm an opponent, you can equip their weapon and make an attack with that weapon as if you are proficient with that weapon and if it is a weapon that can use weapon mastery you can use that mastery for that attack only. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

Your shortswords weight no weight when carrying and has +1 to attack rolls to hit.
Warhammer: As an action, you can choose to shatter the creature's armor while attacking. You make an attack roll with disadvantage that deals 1d12 bludgeoning damage to the creature's armor. If the creature is wearing any armor or has natural armor, until the start of your next turn it has -2 AC for any incoming attacks. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

Your attacks with a warhammer to a creature decreases it's movement speed by 5ft and any attack on the ground makes that 5ft of ground becomes difficult terrain. This feature can only be used once per turn. 
Whip: As an action, you can make an attack to a creature that is within your reach. The attack deals 1d12 bludgeoning damage and the creature is grappled. As a bonus action, you can move that creature to an unoccupied place within 5ft of you. You can use this feature a number of times equal to your proficiency modifier until you finish a long rest.

While wielding a whip your attacks deals 2d4 slashing damage and your reach increases by 5ft.

Critical Chance

Starting at 7th level, when you do a critical hit you can make another attack as a part of your attack action.

Increased Arsenal

Starting at 10th level, you can choose two more weapon masteries from your weapon mastery table.

In addition, your weapons from your weapon masteries count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Weapon Master's Arsenal

Starting at 15th level, you can choose two more weapon masteries from your mastery table

In addition, you gain the ability to observe abilities of any weapon you have weapon masteries on. If you spend 1 minute observing or interacting with another creature outside combat, you gain the knowledge of one of their abilities that they can do with their weapon. If you spend at least 1 hour with a weapon by itself outside combat, you can learn it's properties whether it's magical or not.

Arsenal Upgrade

Starting at 18th level, you have weapon masteries with all of the weapons listed. 

In addition, you can use your weapon abilities infinitely. 

 

Versatile Knowledge

At 3rd level, you gain proficiency in Athletics.

Quick Hands

You can switch to your other weapons as a free action on your turn.