Introduction
A tutorial about how to use any node for any weapon.
What do you need:
- Immersive Equipment Displays and its requirements.
- And a little bit of tweaking with IED.
How to use IED (for the purpose of this tutorial)
First, we'll need to access the IED interface while in game, the default key is "Backspace"
Then we'll need to go to "View>Gear nodes".
P.S.: In versions earlier than 1.7.0, this window was called "Gear positioning". In most recent versions, it's called "Gear nodes":

We'll be using the "Actor" tab and the Player character and the mace as example.
With the "Placement" option, normally, you wouldn't be able to change the node for the maces:

But, with "Unrestricted placement" enabled, you can use any node for the maces, let's choose "Sword back":

Uh oh, now the equipped mace is showing on the "back", but at the wrong position:

No problem, we can fix this by going toggling "Positions" and expanding the "Sword Back" node.
Then, clicking on the arrow next to "Offsets" to add a new condition for when a mace is equipped, because we don't want to change the default position for the swords:

Create a new condition with "Type>Mace" then click on it and toggle "Equipped":

Then adjust the positioning to your likings.
Final result:

What about other nodes that are not available in the dropdown menu?
Let's say, you want to equip a Two-Handed sword on your left hand instead of on your back... Even with unrestricted placement, you can assign some other nodes, like "Hand left", "Hand right", "Spine lower" etc.. But we can use custom displays for that.
Firstly, in "Placement", click on the "Two-Handed" and create a new override (leave the first field empty).
In conditions, choose "Type>Two-Handed Sword" and select the "Two-Handed FSM" node.

Click on the "Two-Handed Sword" condition and toggle only "Equipped":

This will place the two-handed swords on the hip when equipped.
Now, toggle "Positions", then click on "Two-Handed FSM", toggle "Invisible" and "Requires condition list".
In conditions, choose "Type>Two-Handed Sword", click on it and toggle only "Equipped":

This will make two-handed swords invisible when equipped.
Now, go to "View>Display Manager", then to "View>Custom items" and select where to apply (Global, Actors, etc...):

Create a new display for the two-handed swords:

Expand the new item and toggle "Last equipped", then click on conditions and add a new for "Type>Two-Handed Sword":

Click on it and toggle, "Equipped".

Add a new condition with "Extra>Weapon drawn", then toggle "AND" and "NOT". Also toggle "AND" for the "Two-Handed Sword condition":

This will prevent the display from being enabled when the weapon is drawn.
Now, in "Biped Slots", choose "Two hand melee" and untoggle everything under it:

Finally, choose the node and the positioning.
Final result:

P.S.: When the two-handed sword is unequipped, it will appear on your back.
5 comments
To place a two-handed sword on the hips, use the FSM node. To get corresponding animations, you'll need a mod for that, such as Weapon Styles for IED.
Hopefully it will help most people.