So I leveled my toon up till the 40's relying mostly on alternation and illusion, but it feels to strong and doesn't feel that assasin like anymore I feel more of a mage 1 shotting people, and I wanna reroll. I don't want crazy enchanting+smithing+alchemy combos but I do wish to improve my gear so which path would best suit me ? Cos goin to light armor smithing would let me create glass daggers but daedric ones do more damage ? I won't be able to improve my DB armor that much anyway, so wouldn't it be better to go heavy armor smithing for the better weapons?

I took the left side of the tree, myself. I tend to find good weapons more often than good armor(also consider, you have 4 armor slots, only 1-3 weapon slots). But, your mileage may vary.

The two paths for a light armor thief seem to be:
- light armor, allowing you to smith your armor and the weaker weapons, but you will have to find the better ebony and daedric weapons
- heavy armor, so that you can find armor (or deal with low level armor) until you can make dragonscale armor, but you will be able to make the best weapons

Pick your poison, I guess. Light armor blacksmiths are in a bit of a tight spot. If you're powerleveling your smithing, I guess the right branch would be ideal so you can make both a daedric bow and dragonscale armor, but if you're taking it slow... you might want to consider the simple light armor route (probably more immersive, especially if you're planning to use the intermediate armors.).

You can improve the DB armor a decent amount, I'm wearing it with the nightingale mask. Total armor rating is 250 right now which came to "Exquisite" when I upgraded it. I like the way the armor looks, wish I could make a few adjustments to the color and what not, also on a side note is their anyway to switch or change the enchantments without losing the armor?

I'm leveling my smithing right now since I wan to create some Daedric swords to dual wield. I'm most likely going to take the right side of the tree which is heavy armor, since I don't really plan on wearing any of the other light armors really. The easiest way to level it is to create iron daggers, which take one iron ingot and 1 leather strip, which are available at the merchants. I use the one at Whiterun, both the girl and the father have them for sale. Really simple to make, and you can make a lot of them. Brings up the skill quickly.

You have 250 armor with your DB armor with what smithing skill and which perks ?

Hmm I prefer the Shrouded armour mainly because it lets me get the +25% match set bonus with the double melee sneak attack gloves (dunno what smithing skills you need for this armour though).

He got 100 Smithing as that need for Dragon Smithing

Ah yeah, the perks. For Smithing I have the first one which available and the Arcane Smithing which allows you to upgrade enchanted armor. For my light armor I believe I have 3/5 Agile, which comes to 60% light armor bonus, Custom Fit which gives 25% bonus wile wearing all the pieces. Lastly I have Unhindered which doesn't give extra, but make light armor weightless.