So as said in the title, I have some changed and new mechanics that I'm working on.

The background on the world is that there's a continent that the goddess of magic blessed, giving all classes at least some basic magic ability. I've made mechanics for other things such as boons and banes of gods you have different reputations with, and each person has a type affinity, but I mostly want to tweak anything about the immediate combat if anyone has good ideas or sees something unbalanced. Each class also has a special action or ability they can use, which I think gives more strategic opportunities.

• If you and an enemy uses non-light one handed melee weapons, you can roll athletics while wielding one as well to lower the damage with a block reaction
• Big weapons are unblockable, but leave the user open to reactionary attacks
• Holding a small weapon gives disadvantage on blocking, but they have a chance to dodge seen ranged attacks with a acrobatics check against the attackers hit roll.
• Holding two light weapons lets you block and try to dodge ranged attacks, both with disadvantage
• Types weak to another take twice damage, and resistant types take half
• When knocked prone, you cannot block, dodge, move, or cast magic. Heavy weapons are also unusable when prone
• Getting up from being knocked prone is an acrobatics DC of 11 in light armor, medium and heavy armor get 16, and heavy armor has disadvantage getting up
• Spells that don’t roll to hit, or have a radius can’t be dodged by someone using a single light weapon
• You can roll with disadvantage to target a weapon’s durability against the wielder’s sleight of hand

Anything can be explained if i worded it weird and you want to give advice. A block reaction will also half damage on a success.

Some of these are just weird to me.

The rogue ability makes little sense, anyone can use their one free object interaction per turn to take things out of their pocket and anyone can use an action to attempt sleight of hand to pickpocket an enemy, either to take stuff or add to their stuff.  Coupled with everyone getting a weakened version of rogue's uncanny dodge, it seems like rogues are getting the short end of the stick in your game.

Does the monk ability only trigger in 1v1 or do they get the hp if any enemy in the encounter has the same weapon as them?  Do both parties have to have the weapon out in their hand at the start of combat or is having it on their person enough?  Do they get the bonus if they are unarmed facing monsters?

Your overall combat changes make me think DnD might not be the best system for you, or at least not 5e.  There are systems out there that do a far better job of simulating the differences between armors and weapons, 5e is built more for high fantasy and not worrying too much about the details.

Yea, I wasn't getting any ideas for rogues, so that helps if you have any ideas, but the blocking works with uncanny dodge, so they would take a quarter damage if they block successfully.

The monk ability only works if they are wielding the weapons, and they only gain the temporary hit points if they are engaged with the creature, such as if they were fighting 2 goblins, and the monk had a dagger and one goblin had a dagger and a sickle. The temporary hit points would disappear if they switched to the one with the sickle, considering if they had any left (and if they have a party member gang up on an enemy with them it would go away, being dishonorable). And I haven't decided if they get the bonus from fighting unarmed creature, but it seems like it would make sense, because they are still meeting it on equal grounds.

Also yea, I do know these changes are kinda making the fundamental rules different enough that it might be better to use another system, but I like the ways that stats, classes, and flexibility with characters are in 5e. Plus me and my group have only played DnD 5e (But read a lot of other rules of other games).

For rogues, the fighter, blood hunter, second half of ranger, and barbarian abilities could all make sense, or the monk ability if you change it as below.

For the monk ability, unless you foresee your characters being able to choose their weapons based on the enemy they're going to face, I would give them the bonus whenever they're facing an enemy with a weapon that uses the same or larger base damage, not counting the monk martial die.

Also just noticed this, are paladins required to be tied to a god in your setting? In the default setting they are not, making the worshiping action odd for them.

That does make the honor boost much more flexible, so that's a good idea. As for paladins, I guess they wouldn't be able to gain renown with a god if they don't worship one, but they would still be able to charm a humanoid with whatever beliefs they have (the name of the action would be the problem of not making sense).

But it would be very likely for them to worship a god. The gods in this setting are all homebrew, and the goddess of magic blessed the land, letting just about anyone use magic. The main plot point will also be that a horseman of the apocalypse is coming to destroy the continent, so religion can be a large part of the campaign.

Hi BSN. The changes you suggest really do amount to an overhaul of many mechanics. Since 5e was designed to be self-contained, it's hard to see all of the potential ramifications.When making changes, I'd first suggest comparing the new ability to a  preexisting ability to gauge balance.  I'll make a few comments:

• Fighter: this seems to replicate the rules for two weapon fighting.
• Wizard/sorcerer: what do you mean by "free"? If you mean without expending a spell slot, then there's a balance problem. The nearest RAW analog I can think of would be twin casting, a sorcerer option that requires an expenditure of a finite resource (sorcery points).
• Rogue: nothing in RAW forbids this as a legitimate use of a dex (sleight of hand) option. During combat I might even allow a rogue to do something like that as their free "manipulate an object" if proficient.
• Blood Hunter: this is reasonable. Sounds like something I would add to  feat to make shoves, grapples, and other misc. combat actions more versatile. Consider making the shove a bonus action afer a dash.
• Ranger: the attack bonus seems like giving a ranger access to the true strike cantrip. The skill boost is somewhere in power between guidance (a cantrip) and enhance ability (a 2nd-level spell), but for free.
• Cleric/Paladin: having an action replace a spell for free is a balance issue generally. Charming a humanoid is covered by the charm person spell. I would be careful giving that out for free, without a spell slot.
• Monk: is this something that can be done multiple times per encounter? You need to clarify what means by "engage". Can a monk repeatedly move into melee, disengage, then move back in to gain the bonus? I would clarify that it's a once per encounter or short rest ability.
• Barbarian: this is a strange ability. A barbarian in the heat of combat that isn't raging is generally not doing their job right. On the other hand, it could be considered more powerful than the fighter/eldritch knight's 7th-level ability because it would allow a barbarian to make as many attacks as they want, THEN cast a cantrip. Remember that cantrips are meant to substitute for multiple attacks by scaling up with level. Thus a barbarian could essentially be allowed to make two sets of attacks in a round for free. Remember that a berserker barbarian can only make an extra single attack as a bonus action while raging at the expense of a level of exhaustion, which is a huge cost.
• Bard: this is very powerful. Unless the bard is isolated, they'd be able to take a lot of actions more quickly. Again, damage-dealing cantrips are meant to substitute for an entire action's worth of attacks.

The general issue with these abilities is that they allow characters to avoid some cost that's hard-wired into the 5e rules, be that cost actions or spell slots. Tampering with that mix is hard enough to weight when making homebrew subclasses/classes/feats, but another thing entirely when they introduce new abilities that require no class level or spell slot investment on the part of the characters. As for the general combat rules, I'd seriously recommend a different system, or even the earliest (pre-3e) editions of D&D for which there were much more richly specified rules for different types of weapons and armor.

I think it makes everything way more balanced if you make it so that they need to complete a d20 roll to try and use their power, whatever it is.  I was thinking of a new magic system you can see Here.  You can use a similar idea for the extra powers you want to give everyone.  The DC starts at 8 then goes up by 2 (you can always increase this to 4, or 6.  You might even want different classes increases there DC at different rates.) every time they use there power until it resets after a long rest.  Natural 20 is always a success, so even if there DC is 22 (not possible) they can always try for it.  

What I like about that is they can fail to use there power as well.  Plus you can really power up things like the Monk power to where it's more useful to where it no longer weapon dependent.  You can get 1d6 temporary hit points. 

That's my take on it.