it can be a big difference if it is enchanted and crafted plus the damage comes from the person wielding it ever notice how not only does you skill increase damage but so do the perks, think about it if you max out your weapon perks your doing double the base damage plus your skill thats a ton
It really depends on how the damage raises with skill in that weapon.
Case A
If its the same for all weapons, it wouldnt matter, it would just prove my point even more that there is not enough difference between the lowest and highest tier of each weapon.
For example: If max 1 hander adds 20 damage than a steel sword will have 28 damage and a deadric sword will have 34, which is pretty small. With enchants, the steel sword will have 88 and the deadric will have 94. The difference in % is even smaller.
Case B
If the damage is raised by %, like 100% at level 100 in the skill (not including the perks), it would make the higher tier weapons a bit better vs the lower tier ones. They would still do double the damage of the lowest tier.
As you can see, in case A the damage difference is 28 vs 34 and 88 vs 94. In case B, it would be 28 vs 16. Does anyone know which case it is?
Another point that would make or break my point:
How the weapon perk is applied. At max level it adds 100% to damage. If it does it only to base damage, that would make a deadric sword do 28 and a steel sword do 16, which is a pretty good. If it does it to damage after enchantment, then the difference would be pretty minor in using low tier vs high tier weapons.
Last thing is about blacksmithing: Yes its better to have both enchantments and upgrades on the weapon, but is it worth all the extra points? You need a lot of perk points to add 11 damage to a weapon with blacksmith vs adding like 60 with enchantment. Is it worth spending all these perk points to raise a weapons damage to 68 instead of 60?
The answer would be more clearer if we find out how the double damage perk and skill level is applied to damage of weapon. If they take enchantments into account, I say its not worth to spend all those perk points on blacksmithing.