You need to light side. It is common mistake many do even professional knife photographers (and lunde too). But it is so obvious!
Even light from the top does not light sides. So lower one of you lamp to light directly at side. Like you did for your last Batac sheath.
You have at least two lights - I see two shadows (even three I think). So one is for fill light from the top and you may use second for accent light- like your last photo, but movet a bit in front of the sheath. Left side is perfectly lighten but very front is darker (until you think it should be darker).
Background will looks more interesting if you allow that fabric some light folds which create some shadow pattern but not too much...
Just be natural - again, if smart and creative man just pay attention to what he is doing - he will not need too much advices...
Thanks, Vassili.