For a mage I would say all stats go into intelligence. You will probably start off just being a healer for catacombs. If thats the case look for heal mastery on your weapon and armor. Look for enhanced effect on your charms. The higher the EE the higher the heals. If you want to go arena, I would suggest meleeing up to 15 then switch to casting. If going arena look for intelligence on your armor and weapon and EE on your charms.
For a melee character. You would want to have around 110-120 dex at 55 with your gear on. Once you hit that recommended dex pump the rest into strength.
For items:
Weapon- look for the highest EE you can afford. The higher the EE the more damage it will do
Armor- If you are playing catacombs look for EE on the armor which gives you more defense.
If arena look for stats such as strength/dex (dex is cheaper to get)
Charms- Look for stat charms such as strength/dex (dex is cheaper)
LMK if there is any other questions