Great idea! I would only change it a bit: 'the proposal to slow dulling of equipment should be considered as a passive ability for smiths ONLY.'I think the proposal to slow dulling of equipment could be equally considered as a passive ability for smiths maybe.
Make weapons dull faster or whatever rocks your boat I don't care! Just don't go with this idea for discipline.
Make this feature available only for smiths. Have brave (disciplined) warriors perform better in battle.