I just did some testing on TC, and using Dull Copper + powerful in 20 attempts with 1 title I did not get any items that were >100% of imbue intensity. I got a bunch of 50% HSL and 87 on either HLL or HML... I am trying to make a 100% HML longsword, so I need 115% intensity (87 is max imbue). I know that copper can do it. I assume that shadow can, though I find copper hammers easier to come by. I have a bunch of dull coppers laying around, so even if it took me a bunch of tries, no problem.