I should also mention that Spiny is real bad now. Only +0.5 bonus damage at lowest dura (From my experience at least).
Bonus from spiny and stonebound modifiers depend on how much durability was actually used, in uses, not percentage (however it is not linear dependency anymore since T2 tools). So a bonus from spiny on a manamana sword will be a lot better than on paper sword. Also it stacks, two parts from cactus will give you more spininess than one part. I think bonus from two cacti part at 400 durability lost will be the same as bonus from one cacti part at 800 durability, but I haven't tested this scaling extensively.