Use the following tricks for easy early leveling with shield and knife (levels close range, shield, and defense).

Warrior: Intense shield and knife creates intense defense with a decent attack.

Spiritualist: Having a Spirit knife that increases FP recovery by 500% and will help you maintain a spell fiesta without many potions. A shield could benefit if you are dependent on not dying.

Ranger: When the Long Range skill is maxed, use this combo to stay powerful and alive. Defense is not given much to a ranger. Leveling close range can be difficult. Intense works well.

Specialist: Intense shield and knife really protects the health they lack. Long range weapons will be useful if they prefer avoiding damage altogether.