When going through the foggy part of the shaded woods you are often attacked by some unseen attacker. I'm assuming ghosts or invisible attackers. Is there any way to make them visible to have a fighting chance?
They are not invisible, just very hard to see when the camera is moving. Move slow, don't move the camera too much and look for the edges of the figure. Once you find one, move straight towards them slowly, and look for them to notice you. They roam around a little in short patrol lines.
Stop moving and rotate your view as best as you can to keep them in front, since a backstab is probably going to be a one shot kill. When they get close enough to commit to combat, attack. When they take damage, their health bar appears briefly.
It is difficult to judge because the closer they are, the more your player model blocks them from view.
If you have to retreat, either turn and sprint, or backpedal, trying to move your view slowly enough that you can still track them. Try to be mindful enough to retreat along the path you approached to avoid attracting the attention of a second or third one.
Do not open any chests etc. before you have taken care of the one(s) nearest the object.
The worst part about this area is that the other players' ghostly apparitions are easily mistaken for enemies. The enemies are less grey.
If you're playing the Scholars of the First Sin edition, you've got an option that gives you a better chance against these enemies. Obtaining the "Eye of the Priestess" item from Frozen Eleum Loyce will make all ghost enemies in the Shaded Woods completely visible and capable of being locked-on to.
No. Until a mod comes out for the PC version there is no way to make them more visible. They do have a very faint silhouette though.
This needs confirmation, but if you're with a lit torch, you can see their shadows. I never tested this, since i was running like hell trying to get the itens and keep myself from get killed.
The easiest way to see them is to have both brightness maxed out, in setting and on tv/monitor. I can easily see them and their attacks
You can use weapons like the Arced Greatsword - any weapon that swings wide but doesn't have a lot of recovery time is great because it gets their health bars to show up.