One possibility is for you to use this weaponless Ranger model coupled with weapons that were pre-animated on top of the player model (although those are enhanced models):
http://gfx.quakeworld.nu/details/312/vwplayermdl-vwep-prerequisity/
http://gfx.quakeworld.nu/details/238/trickles-vwep-package/

Another thing you could try is to animate your models while taking references on top of the player's animations (especially if the player's model has no weapons in hand beforehand). Take note that they have to be separate models. Once you animated the weapons with the same amount of frames as the player's, you could easily do something in QC like show the appropriate weapons depending on the used slot, and rendering them invisible once he dies. 

http://forums.insideqc.com/search.php?keywords=vwep 

Make sure you use capnbubs model 

Make sure you use capnbubs model 

Yeah that's how the sword is done in my rpg mod. Qc is included iirc. I'd the frames match, it's almost trivial. 

If you're not worried about limiting yourself to options that only work in darkplaces (and by using IQM you're certainly eliminating most options), then a good place to look for some skeleton "How to" guides is dpextensions.qc

That's a qc file which comes with darkplaces, and give you a list of all the extensions it supports. MOVETYPE_FOLLOW is one option which will work in a similar way to how Quake 2 does weapon models. However, the entity will be visible to the player it's attached to, which isn't ideal.

Another approach is to look at the docs for setattachment and DP_QC_GETTAGINFO. I'm not sure if DP_GFX_QUAKE3MODELTAGS works on IQM, but I've used it with success on MD3 models, so it's a good thing to play around with. setattachment has the advantage that entities attached to the player are not drawn from that player's first person view.