word choice - Someone or something small yet capable of having big influence?

Seminal:

adjective

1.0 (Of a work, event, moment, or figure) strongly influencing later developments:

2.0 Of, relating to, or denoting semen.

2.1 Botany Of, relating to, or derived from the seed of a plant.

ODO

The meaning of seminal is big influence, the connotation is small.

With just ten sentences uttered over a mere two-and-a-half minutes, Abraham Lincoln delivered his seminal Gettysburg Address that continues to shape politics into the twenty-first century.