While it may not seem it at first, your Academy eventually forms a big factor in your strength. Its potential keeps increasing as you level up. However: It takes a lot of kyanite (and time for non VIP) to max out, slow levelling helps this process as you’ll get more kyanite and time per level.
At level 41, you can raise your BR (battle rating) by spinning the Blessing Wheel. Doing so will boost the Academy skills up to 200%, thus making you much stronger.
The minimum bonus is 10% (110% tech effects). The blessing goes higher (never lower) with each spin, to a maximum of 200% (300% tech effects). For example: You have 400 PATK from technology. You level up to 41 and receive the Blessing Wheel with its minimum bonus of 10%, and you now get 440 PATK from technology (110% * 400 = 440). Spin several times until the wheel shows 100%, and you now get 800 PATK from technology (200% * 400 = 800).