In our dojo we train both empty handed and with weapons and a new student can start weapons from his first week.
I know that working with weapons effects alot of my empty hand techniques and makes them better.
For example- suburi number 1 with bokken- it seems like a simple movement (raising the sword and bringing it down) but there is much more to it- not to put stress on the shoulders, let the hands fall in a normal way, near the body and not extended forward etc... Then when you do empty hand techniques that have that movement of the hands, you begin to understand why that technique wont work when you bring up your shoulder, when you work with the force of your hands and not your center...
I believe weapons training isd very important and helps in understanding many of the empty hand techniques. I am not sure, but I think that many also came from weapons movements and were diverted into empty hands.
All this I'm saying after just a bit less than 3 years training and I have been doing weapons all this time soon.
Also, a guy from my dojo that started 2 months before me, moved to another city and started training there. He said they don't work with weapons at all and that they don't understand the importance of body and hand movement in certain techniques, which we understood through weapons training.
Well, hope I didn't bore you!