They don't literally have a defence level, it's just a way to explain the mechanics of woodcutting (and mining) simply as in essence they boil down to the same raw mechanic as hit chance: Your tool has a particular accuracy or chance to hit. The object being affected has a particular defence or chance to avoid being hit. Tools roll a random number (say between 1 and 100) and specific numbers are assigned as hit or miss, higher accuracy means more are assigned as hit. The object 'defending' itself will also roll and again specific numbers are hit or miss, higher level trees and ores have more numbers assigned as miss. To get a resource from an object your tool has to land on hit and the object has to land on hit also. For tools it means a higher tool has more chances to get resources and thus you collect quicker. For trees and rocks it means a higher one has more chances to stop you getting resources and thus they take longer to collect. This mechanic is basically identical to how attack/accuracy and defence works in combat, all that is missing is the strength/damage roll which will decide how much damage the attack does (minus any soak or reduction effect supplied by the opponents defence) Wow, never knew this! Really helpfull information :D