I noticed this happen and couldn't for the life of me tell if it's normal or if it might be a faulty ini. setting.
If you load an arrow and walk towards a wall with your bow, does the arrow/bow sink into the texture? (As if the weapon had noclip) Or should the weapon stay 'over' the terrain?

In 1st person my bow stays over the terrain, but in 3rd person it clips through. :shrug:

Right, I wonder why that is then, in first my weapons still go through terrain...
If anyone knows what governs this I'd appreciate a heads up, cheers.

meh, no big deal.
First, not all weapons have they hitboxes formed exactly after their shape. Second, engine limitations. Third, bethesda didn't gave such things much thought, since it's quite unlikely you'll see such clippings (they thought, who activates 3rd person view when shooting with a bow anyway?)
Thus, there may be some minor clippings and they do not matter.