I always go smithing on my characters, but I just realized something. My assassin will use clothing and dragonskin, so that is armorcap. No legendary armor can top that. Also, I plan on using Mehrunes razor and blade of woe. With the 15x+15x times 2 = 64x damage modifier, melee weapons is covered. Then I thought "Hey I will need a good bow!", thing is... I will be using a bound bow!

Using Mehrunes razor with the goal being [MINOR DB:DLC SPOILER] as replacement later on, using bound bow, and using only clothing with dragonskin for instant-armorcap - wont that mean smithing is completely useless for my character? Im pretty sure it is so, but I want to make SURE Im not missing anything.

If you're wearing no armour and no weapons save Mehrune's and bound weapons, you need no smithing at all.

Yup.

You may want to level up smithing to 100 at some point. Just for extra atribute points and perks to use elsewhere. Smithing is effortless to level if you wait until late game.