I've now put the mod in question on CivFanatics. The thread for it is
over here. It's a bit bothersome to screenshot in mid-attack, but this picture should give you a quick idea of what it does:
Copying the game's base .fxsxml and .ftsxml and replacing the bones with ones I actually have, I've reused Civ5 effects for as many of the units in that mod as I could. One tip I can give for if your animations stutter is to look at the timing of the effect compared to the length and timing of your animations. If you run out of animation before one of your effects is scheduled to take place, it will (in the best case scenario) keep running the animation until the appointed time. So if you have imported short animations, you'll want to adjust the effect timings to fit. If the effects include a sound effect that lasts longer than the animation (this can happen with Great People) there's not much you can do.
I was asking for help earlier because I had some trouble getting the redone archers to work, but I've now successfully redone them at the proper size, making the arrows the proper size as well. If you're importing CivIV units, the way to get it right the first time is to use the Scale Correction value when importing the .nif. As a rule of thumb, assuming the unit is properly sized in CivIV, you'll want this value to be 10 times the Scale value of the corresponding Civ5 unit in ArtDefines_UnitMemberInfos. Then use the base Scale value as your own Scale value for the new unit, thereby keeping the effects at the appropriate scale. (Example: regular Civ5 Archers have Scale 0.14000... in the ArtDefines_UnitMemberInfos table, so you'll want to import custom archers with Scale Correction 1.4 and give their entry Scale 0.14 in the database.)