Him being the only person actually using ranged weapons, can't equip them and the ammunition at the same time.
If he equips the bow/crossbow, then the arrows/bolts it will unequip the bow and vice versa. (itemlevel doesn't matter)
I actually have yet to reconfirm this issue myself, but due to me being stuck at work for the next 6 hours I won't be able to check if the server log is showing anything, and if it's something I can replicate with my character. (also I'll do another recompile once I'm home, just to be sure)
All I know is that equiping items like Bomb Core or Bibiki Seashell (those ranged items you use for stats only) work fine .. also the BST Food and the items used to call familiars do what they are supposed to do.
The server itself is a "vanilla server" which was updated on Sunday .. and his client is a fresh install, updated not even 24 hrs ago.
Everything else seems to be working, just the ranged is ruining his gaming experience (and as of today: my nerves, because that's all he's talking about .. I had to threaten him with Mordion Gaol, to shut up for now
). So any pointers where I could start looking for the solution? And if it's clientside or serverside (If needed screenshots and logs will be provided as soon as I'm back home)
... Someone's going to get sent to jail for this 
(and for the fact that he couldn't create an account here himself and just ask)