I've enchanted a ring, necklace, and apron to each give me a 20% bonus to smithing which is already at 100. On top of that, I have some blacksmith elixirs that give a 50% smithing bonus. Using all these items at the smithing wheel, I've been able to improve my ebony greatword and war hammer to legendary status without the perk that allows me to craft ebony armor and improve it twice as much. The damage output on these weapons is pretty nice.
I've been grinding like mad to get the four perks I need to get to advanced ebony smithing, but then I got to thinking: When I do get that perk, will I experience even higher damage/armor ratings when improving ebony gear or am I pretty much able to use my magical items to augment my smithing ability as far as the game will allow?
Best Answer
There currently isn't a weapon damage cap, so you'll be able to create stronger ebony weapons with the ebony perk than without. This goes for all weapons and their respective smithing perks.
That answers your question, but I think maybe the question you should be asking is, "How easy do I want to make this game".
I'm a level 57 with 100 in smithing and all perks. Using only 25% Smithing Ring and Necklace, I can great 200+ damage bows and 100+ swords, before dual enchanting them with additional stats. I'm on Master difficulty where I do half damage, and I'm still incredibly deadly and near invincible. This is without using any potions to boost while smithing.
So if you want to create the stronger armors/weapons, you'll need the perks, but I wouldn't say you need them to become super powerful.