The rules are quite simple on soul number, The weapon and Meister must have the same number to use each other in battle. But it is very much possible for the Meister to use other weapons through training.
The scale is between 1 and 20, picking OOC is allowed for the Meister and Weapon to match, but no mass picking of the same number.
With Same number weapons Meisters can easily train their soul wavelengths to match each other.
25% Control: 1 topic of training - This allows for low level techniques and less electrical feedback.
60% control: 3 topics
100%: 5 topics
When trying to build a new Number, you must train with a weapon that does not have the same number as you. By doing so you can slowly gain the ability to use weapons with that soul number.
10% control: 5 post - Extreme electrical charge causing a small paralyzing effect for a post.
30%: 1 topic of 8 post - Electrical charge
50%: 3 topics of 8 post - No electrical charge
80%: 4 topics of 9 post - Able to sustain a resonance of 1 post
100%: 5 topics of 13 post - Soul Number learned.
Reapers however are a special case: there soul numbers vary from 1-5 and they are only able to learn 3 of these until they have unlocked all of their Reaper marks. 1 equals the first 4 spots of a normal soul number, 1-4, 2 equals the second 4, 5-8, 3 equals the third 4, 9-12, 4 equals 13-16, 5 equals 17-20.. The way the reapers train their numbers is the same as normal meisters, but by choosing one number from the 20, to get the number in their 4 that they wish to obtain.