The problem at hand
I'm fairly proficient with the usual pathways for getting frost or fire or radiant damage combos/optimization going with regular weapons or using holy symbols, but I am new at trying to optimize damage for ki-focus implements. My usual method of grabbing a weapon that can apply a damage type to all attacks made with that weapon is out the window. Aside from the class itself being homebrew, the game is run RAW and any and all items and feats that I could qualify for are available. I just hit level 8 so I have a feat to spend and am also willing to retrain a feat as well (improved imitative) so I have 2 feats to work with and I have not multi-classed yet.
Currently I'm running a custom class for the game based on the Geralt of Rivia which functions very closely to the Executioner class in 4e. I have poisons/bombs that are daily use items that I craft in much the same way as the Executioner. The Witcher class is a striker with a heavy controller feature. My at-wills are all weapon attacks without any special keywords. I do have more regular (vs. essentials) encounter powers (based on the aard signs) which have the implement keyword. There is no common theme among the encounter powers as they all target different NADs and if they have a damage type, it is different from the others. The poison dailies are applied to my weapon and augment the damage of any weapon keyword attacks while the bomb attacks are made using and have the implement keyword. I have access to the Venom hand feats as part of the class and for the class has both the Martial and Arcane power source, so any feats simply requiring either power source (like Arcane Mastery) are available to me.
Current level is 8, but the campaign will go on through paragon and I think into epic (will need to check with DM). I am seeking to optimize for now, and onward. I'm looking for any feat and item combinations for implements similar to frostcheese or radiantcheese for regular magic weapons. Here's the character sheet as of lvl 7. https://skydrive.live.com/redir?resid=723A28155692C47F!554&authkey=!ANK_HRfu03BkkZo
Please asks questions in comments for clarification!