Melee
The basics
This is the stuff that anyone can do, you just need to know that it exists. Learning the basics will put you ahead of 90% of the community.
Defense
Defending in Holdfast is extremely straightforward. You have 4 block directions, which will be covered in pairs. All weapons can block in Holdfast, except for the carpenter's axe, the sapper's tools(His sword can still block) and any of the tertiary DLC weapons.
Up and down block:
These are the 2 block directions you will be using the most, since all musket attacks will be one of the 2 and 50% of sword attacks are up or down.
Performing these is rather simple: Move your mouse in the direction you want to block. I.e. if the incoming attack is a down attack, you will have to move your mouse downwards, then click right mouse button to block it(The light around your crosshair indicates which direction you will block if you would block now). Same goes for an up attack. You have to block in the same direction as the incoming attack is in. Even if a down attack is aimed at your head, only a down block will block it.
Blocks happen near-instantaneously and have a very slight grace period after being let go of. I recommend you practice these 2 blocks, as a lot of new players continuously fail to block the correct way due to bad mouse movement.
When learning and practicing block directions , instead of moving your mouse the "expected" amount of distance for an up or down block, you should over exaggerate the movement, moving your mouse to look down on the floor for down blocks and looking above the enemies head for up attacks.
As you improve your skill you will get better at blocking and the distance you move your mouse will be reduced.
Left and right block:
These blocks should only be utilized against a sword, and have no use otherwise.
Everything from paragraph 2 from "Up and down block" is true for left and right blocking, except that you need to move your mouse leftwards to perform a left block, and rightwards to perform a right block.
These 2 blocks do not need to be practiced much, and should be learnt automatically with experience.
Misc.:
Movement is another important topic, however there isn't really much to say about it, and its better learnt from experience. However, as a rule of thumb: Whenever your opponent starts attacking try to distance yourself away from your opponent, while also continuously facing said opponent. Reverse is true for attacking.
Offense
Offense by itself is pretty basic, and there is a lot to talk about it on basic levels.
Up attack:
Similarly to an up-block, this attack can be performed by moving your mouse up+pressing the left mouse button. Holding the left mouse button will cause you to hold your attack, however 99% of the time you should simply let go of it instantly. This attack is slightly shorter, but also faster, though the difference. is minimal.
Down attack:
Similarly to a down block, this attack can be performed by moving your mouse down+pressing the left mouse button. This attack too can be held, though the same thing applies to a low attack as to a down attack: You should rarely hold it. This attack is slightly longer, but also takes slightly longer to finish, though, as with an up attack, the difference is minimal.
Left and Right attack:
These attacks can only be performed by swords, and can be performed by moving your mouse left/right(left for a left attack, right for a right attack). These have no difference between each other except for their swing direction. (This section may be expanded upon additional testing)
Additional notes:
Attacks have 2 phases: A windup, during which you cannot hit, and a "thrust" phase, during which your character will thrust his weapon, and can hit opponents. Attack also have a very small "linger" phase, where the bayonet isn't being thrusted anymore, however, it can still hit opponents.
There is a built in sensitivity lock for all attacks, however, by blocking and then attacking(pressing right mouse button->pressing left mouse button->letting go of right mouse button) we can bypass this lock. We will exploit this in the spinning section of the advanced part.
Dragging your attack too much(moving it around, spinning) will cause you to deal less damage.
While attacking your movement speed is slightly slower than when not attacking. On a basic level this shouldn't affect you too much, but if you're chasing someone only attack when you're sure to hit
Damage mechanics:
Attacks actually can deal different damage depending on where you hit and how you hit. We will quickly go over them here.(Note: We're talking about line infantry vs line infantry combat, which is the general competitive format)
Action Hits to kill
Upper body hit+no drag= 1
Upper body hit+drag = 2
Lower body hit+no drag= 2
Lower body hit+drag = 2
As you can see, hitting the upper body deals more damage than hitting the lower body, and dragging decreases the damage you can do. There isn't a lot more to talk about this, and so this section ends.