Subtle

adjective

1. pleasing to the senses in a mild or nuanced way : delicate, elusive
2. difficult to understand or perceive : obscure sense 1c
3. clever and indirect : disguised in purpose
4. gentle sense 1aalso
5. having or involving keen perception or insight
6. highly skillful : expert
7. cunningly made or contrived : ingenious
8. artful, crafty
9. operating insidiously