Magic effects, from magical equipment or spells, increase the capabilities of the affected Character by one step for each numerical bonus. For example: a Character who is Familiar with climbing who dons Boots of Climbing +1 is treated as Trained in climbing for as long as they wear the boots; if they were already Trained, they would instead be an Expert while they had the boots on.
Expertise can never surpass Master level
A Character can never exceed the level of Master. If the boost from a magic item would put them above that level, the excess bonus is converted into extra dice instead. Example: a Master climber donning Boots of Climbing +1 cannot be raised to more than a Master so they gain one die to their dice pool instead.