An untyped bonus is a bonus where there is no type stated (such as enhancement, sacred, or inherent). As Pawsplay stated, you couldn't do this twice to gain double the effect.
The Power Surge would stack with Rage (except you'd need to be Chaotic, impossible for a Kensai), and the Dwarven Defender's Defensive Stance, both of which give untyped bonuses to Strength.
Any bonus that is not specifically stated is untyped. You can tell in the line that talks about the bonus. Specific bonus are named. The text would say something like "this is a dodge bonus to AC" or "this is an enhancement bonus to STR" or something llike that.