There is less than a 1% difference between infused and sharpened with weapon damage glyphs. So it comes down to play style. If you do Light and Heavy attack weaves, then go infused for the glyph boost. If you are more skill only, then sharpened or even precise (which also falls into the 1% range).

Note I base this math on a recent thread I can't find where all the main traits were compared in over all builds. Bottom line, not much a difference. Infused edges them out, assuming you do the LA or HA to proc.

I would recommend Nirnhoned. Your not on your back bar often enough to have the Infused help you that much with your DPS. Weapon damage enchantment should be put on off hand Dual Wield weapon. The light weaving and heavy attacks will proc the weapon damage enchantment often enough.

Big thing to remember is that they made a change where back bar enchantment will not proc when you are on front bar, this used to be the case but they removed it, so back bar Infused wasn't as worth it after that.