Good quality tools should last a life time and will work so much more effectively when they are kept in good condition - just ask any professional.
This handy sharpening whetstone block will keep your tools nice and pristine.
Something about a good workman never blames his tools and all that....
For some of the best secateurs see here:
or for smaller hands try Sophie Conran Secateurs
And not forgetting the absolutely sumptuous Okatsune Japanese Pruning Shears