Arelith

Currently, Shamen are the only class with the "Use Poison" ability that do not get an increase to the DCs of their poisons, and to be honest, this is sorely needed.

Of 24 Arelith poisons, only 5 have a DC of 20 or more (one being Drow crafter only). Most are below 15, one even as low as 11, and they just do not cut it.

Perhaps against some low fort PC builds they might be useful, but for PvE they are utterly useless. Even a DC 16 poison against the goblins on Skaljard (a level 6 or 7 max writ?) fighting solo through the whole camp I might have successfully poisoned maybe 4 goblins? Considering the materials needed to craft some of these poisons that just leaves them utterly worthless.

If you are concerned about Shamen entering the assassination niche by getting more powerful poisons, maybe offer them a duration buff instead. Hours per class level perhaps? This way a 3 level dip on an assassin would not give outrageous durations.

I'm not a mechanics wizard, I am sure other people will be able to judge how things can be balanced between PvE and PVP and any issues between a Shaman with poisons compared to Assassins/Blackguards.

Or alternatively, anyone else have any ideas how Shamen can make use of Use Poison in a new and unique way to give the class some flavour?

Does anyone really effectively use poisons at all? I had an assassin I intended to be a poisoner but it was just so much trouble with negligible result. Poison seems like something that works best against PCs from monsters in PVE as it's a slowly building nuisance but in PVP the fights usually over before poison mattered. But if someone has great success with it I'll stand corrected and try again myself.

I might suggest shamen be able to cast the poison spell on a weapon to give it a unique enchant instead?

Even in PvP poison isn't worth it. You're basically fishing for 1's and the secondary effect never happens in a fight. Until recently the poison also didn't stack with essences, but I'm unsure if they fixed with the recent on-hit bug fix.