ok, here explained well:

The most basic weave in this game involves putting a weapon attack before a skill, so they basically both fire at once. Skills have a global cooldown of approx one second. Take force pulse for example. If you spam the skill over and over, it wont fire faster than about 1 per second, even if you push the button 5 times a second. Weaving a weapon attack increases DPS because you are adding an extra amount of damage into that 1 second window.

There are generally two types of weaves in this scenario, a light weave and a medium weave. Both have pros and cons:

Light weaving means you click (don't hold) the left mouse button (weapon attack) and immediately follow with a skill. This results in a light attack and a skill firing at almost the same time. The advantage to this is that if you do it perfectly, you can generally get a slightly faster rotation. In other words over a long fight, you will get a few more skills off. The downside is that it is much tougher to do from a button pressing standpoint and it is tougher on resources.

A medium weave is very similar, but instead of clicking the mouse button for a light attack, you hold it down for about a half second and then release and press your skill button. This is generally much more fluid and easier to perform. It is much better on resources because you can adjust the length of your weave as your resources get lower. If you are low on magic, you can hold the mouse button a little longer to by yourself some time to regen. The downside obviously is that it is generally a touch slower. The weapon attacks will register as heavy attacks. We call this a medium weave, because you really arent doing fully charged heavy attacks, even though that's how it appears on a damage report.

Basically, if you click the LMB it is a light attack. If you hold it down until the weapon fires on its own, its a fully charged heavy attack (should be noted that most anything that says fully charged heavy attack on weapon sets or tooltips only applies to this type of heavy attack). Anything in the middle of these two is informally known as a "medium" attack. So if you hold your LMB down for say 0.8 seconds and let go, the result will be a "medium" attack.

On a staff there is an easy way to tell. One fire ball is a light attack, two fire balls is either a medium or fully charged heavy attack. I would start with a medium weave as its much easier to do, and the DPS loss is negligible for most. I still do medium weaves in trials and can pull 40k+ on most trial bosses. That being said, the crazy DPS out there pulling 50k are almost certainly light weaving (not suggesting the difference between the two is 10k, just trying to give some insight).

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