In my story, "Fox Mage's Reincarnation", one of the aspects is that the characters have rare and special Abilities. I've hit a roadblock where I'm trying to create a monk/weapon master character and I have no idea what Abilities to give them.

I'd also appreciate any suggestions for other types of powers for characters such as Rogues, Berserkers, etc. Though that's less important right now.

monk usually fight barehanded or hit the enemy with a staff. for abilities they usually go CQC and healing magic

and weapon masters can use several different weapons so sword skills, axe skills, and so on depending how many weapon the characters is going to use. for magics, there is the "wind slash" and so on.

does that answered your questions?

Somewhat. The weapon skills don't align to what I had in mind according to the System I set up for it. I could give them some elemental abilities and even go full Avatar with the character, but that would be slightly repetitive.

Depends a lot on the setting of your novel. But a few ideas for a magic skiills for monk or weaponmaster that come to mind are:
-Change the shape of the weapon during combat.
-Phantom/magic hands that hold weapons or punch enemies.
-Echo strikes (after the attack there's an echo attack that hits the same place) .

You can also try going for "movement based" or "Perception based" abilities. Not everything has to be a shiny elemental blast. 

One such as sensing an enemy behind you for monk based on air or feeling ground vibrations (avatar) 
Same with rogues, can go for "stealth based" instead of blast based. 

Berserker you probably want it to be blasting though. xD

Lean into the archetype and think of what makes up such an identity. Monks are seen as spiritual warriors with impressive discipline and rare knowledge. Weapon masters can make anything and everything into an effective weapon, and are even better with the real deal.  Combine them and you get more of an idea of where to go with it. If I were doing it, I'd give the character an ability focused on never being left defenseless. Maybe it lets him/her reinforce whatever they hold in spiritual energy. and it's called 'Divinity Douse' or something like that. It's up to you ultimately. Same thing goes with the Rogue. Berserker, and anything else. Think what purpose those jobs have, and give them what they need to fulfill their niche accordingly.

It depends on your restrictions and wiggle room on your "powers." How powerful are abilities, and how restrictive are they? In my WIP the more specific and restricted something is the more powerful it can get in it's respective use. The more flexibile a power is, the slower or more taxing it is to use. 

Imagine if someone had "vitality draining touch" as their power. That would make for an interesting Monk. They might need to learn to fight bare-handed so they could get as close to skin to skin contact as possible to use their power. They might learn wrestling moves and holds because just locking someone up would be enough to win the fight by draining them as they healed themselves. It might even lead to a spiritual side as they realize all life is connected and transferable leading to a more Taoist outlook on reality. Conversely, it might lend itself to a Berserker style of combat where someone is willing to forgo defense completely to get in close secure in the knowledge that as long as they can attack, they can heal so it doesn't matter if they get hit. It could lead to near-frenzied attacks and running right into arrows, blades, or fire, just to get close enough to hurt someone. That much pain might build up a tolerance, or an addiction, that influences them in other ways. Even a slight wording change on something so simple, and if it is restricted to skin or can be used through a weapon, can make one power drive someone towards a path of a monk, or a path of a berserker. 

I find that a lot of the "person has special power" problems are solved by thinking how an individual might see that power and then figure out how to use it on their own. Just about anything can lead someone down a path if they want to go that route. You can make nearly anything work to be what you want it to be, just think of how a character might interpret it and run with it. 

Their is always the idea for monks of spirits. 

For a weapons master you could have him summon spirit weapons. 

Another idea is the classic armory abylity where he can bind weapons to himself and summon them at will. 

Other then that there is more passive abylitys like a calm mind or some type of battle calculation abylity. 

Some sort of flow state he can enter where all of his moves connect to each other. 

You can look up inside the Diablo wiki for the monk class abilities.
here: https://eu.diablo3.blizzard.com/en-us/class/monk/active/
It is mostly hand to hand or staff using warrior, but he does have some magical abilities that help against dark creatures and cetera.

For rouge, they mostly use daggers and short swords. They are dexterous, meaning you could give them acrobatic abilities mid fights, like them doing a backflip or hand spring.
They are also great for lock picking and stealth. meaning you could also give them techniques to go invisible \ poison enemies.