Here are some things you can try - I'll start with a down and dirty method, and following that will be a full explanation of what I have learned about particle effects to help you maybe come up with some other ideas to try.
I do not have the particular mesh you are referring to so this may not work at all but ... try implementing it as a clothing item using these steps (if you already know how to do this, my apologies... there may be some out there who don't):
1) create a body part and tick the clothing mark and select neck - the art file is your mesh
2) create a clothing item as a left (or right) glove and select neck on the first pulldown - now pulldown the male clothing bar and select (scroll to find) the id of the body part you made in step 1
3) make sure your NPC is not already wearing hand covering items, and drag the clothing item you made in step 2 into his inventory - save.
4) that's it - in game your NPC should now have that effect on him - it may appear in the wrong place, if so read on.
5) (optional) for lulz drag the item again onto a table or something and pick it up in game and wear - the effect should be on the player.
the nitty-gritty:
For particle effects that swirl around (or behave anyway you want them to for that matter) an NPC, creature or the player, you first need a mesh that has a NiBSParticleNode. To find out, open in NifSkope and expand all the lines until you see it. If you have the CS disk or have unpacked Morrowind.bsa, find the mesh "Ex_waterfall_mist_01.nif" - it has a particle node. The template nif I personally favor is "W_art_katana_flame" which sadly I have no clue what mod I got that one out of. Now, open your mesh with the particle node in NifSkope. Expand all the lines and locate "NiParticleSystemController" and left click. In block details you should see a slew of listings with numbers. These listings allow you to change the shape, rate, speed, etc etc of the particle effect. Before we continue:
*important* backup your particle nifs before you edit them. The first thing I do when opening in NifSkope is save as a different filename. These things are very easy to corrupt to the point where they won't load in NifSkope and may crash MW in game. Make changes slowly and test test test - save save save. School of hard knocks is how I learned this rule.
Sometimes when saving an edited particle mesh you will get warnings in NifSkope like "link points to wrong block type" - if so, try to load it again, if it loads, 9 times out of 10 you are ok and can ignore the warning and keep using that mesh with no problems.
If you don't see anything when you press play, find "NiMaterialProperty" and set alpha to 1.0 to make it full visibility. Put it back where it was when you are done fiddling with other settings (see discussion below about alpha).
Back on track, you can change the shape and other characteristics of the particle stream by changing the numbers and press play to watch the effect in motion. But what if you want to change the color and appearance? well, then you will need a new texture. Particle textures should have an alpha channel or they wont look right at all. A targa with alpha (.tga) works well. Browse you textures folder for examples. If you create your own, make sure it has an alpha channel - alpha controls transparency - lots of info on the net to help you wrap your brain around alpha. Anyhow, make sure your mesh has a "NiAlphaProperty" with flags set to 237, and you can control the degree of transparency in "NiMaterialProperty" (alpha value is right below glossiness). 1.0 is fully visible and 0.0 is completely invisible, so 0.5 would be half-transparent.
The last thing you need to do is reposition the effect on your NPC. Do this in the parent NiNode of the particle effect node (which would be a NiNode), in most cases it's the "NiNode" on line 2 or 3 - the text should say something "emitter". Now for this line, in block details, you will see "Translation" and "Rotation". You can move the effect around by changing the x y and z values in translation, and change the angle in rotation. This will be a process where you need to look in-game at how the effect changes on the NPC each time you change the values. It will take time to get it "just right". One last thing you may need to do is change the flags on this same parent NiNode to 226 - this will (kind of) "skin instance" the effect so it moves appropriately when the NPC bends or turns etc. I just now while writing this discovered this detail so my knowledge is presently sketchy on this part. Just goes to show you learn something new every day.
In theory you can change an existing particle effect nif to do whatever you want to include things like smoking pipes, spilling drinks, etc. aside from just magical auras. Hope it's helpful and any questions can be answered in the construction set forum area because here in mods its way too active to find old threads. Cheers.