In The Elder Scrolls: Blades you will eventually reach a point where just bringing your best gear will not be enough to defeat the different enemies you encounter. To get past enemies at this point you will need to know exactly what type of damage your weapon deals and what the enemy weaknesses and resistances are so you can take advantage of them. Swords deal Slashing damage, Hammers and Maces deal Bashing damage. Axes are for Cleaving damage. The elemental damages can be either done with spells, or they can be imbued on your weapon.
Bandit
Weakness: Poison
Resistance: Fire, Shock
Bear
Weakness: Shock, Slashing
Resistance: Bashing, Frost, Poison
Dragon
Weakness: Shock, Slashing
Resistance: Bashing, Frost, Poison
Dremora Raider
Weakness: Frost, Slashing
Resistance: Cleaving, Fire, Poison
Dremora Warlock
Weakness: Frost, Slashing
Resistance: Cleaving, Fire, Poison
Goblin Caster
Weakness: Bashing, Frost
Resistance: Fire, Shock
Goblin Warrior
Weakness: Bashing
Resistance: Poison
Mercenary
Weakness: Poison
Resistance: Cleaving, Fire, Frost
Necromancer
Weakness: Poison
Resistance: Fire, Frost
Nether Lich
Weakness: Fire, Slashing
Resistance: All Others
Outcast
Weakness: Cleaving, Shock
Resistance: Bashing, Fire, Poison
Skeever
Weakness: Fire
Resistance: Poison, Shock
Skeleton
Weakness: Bashing, Shock
Resistance: Fire, Poison, Slashing
Spider
Weakness: Cleaving, Frost
Resistance: Poison, Shock, Slashing
Spriggan
Weakness: Cleaving, Fire
Resistance: Bashing, Frost, Shock
Thalmor Agent
Weakness: Poison
Resistance: Fire, Shock, Slashing
Troll
Weakness: Bash, Fire
Resistance: Frost, Shock, Slash
Wight
Weakness: Cleaving, Fire
Resistance: Bashing, Poison, Shock
Wisp
Weakness: Fire
Resistance: Bashing, Cleaving, Frost, Poison, Slashing
Wispmother
Weakness: Fire
Resistance: Bashing, Cleaving, Frost, Poison, Slashing
Wolf
Weakness: Shock, Slashing
Resistance: Bashing, Fire, Frost
Check out our Best Weapon page to find out what the most effective weapons are against the various enemies.