'a weaker influence' is a correct and usable phrase in written English.
This phrase can be used to mean that something is having a lesser impact, influence, or effect on a situation. For example, "The increase in technology has had a weaker influence on the local economy than expected."
Concentration polarization is shown to have a weaker influence on the full-scale RO process performance than the thermodynamic restriction.
On the contrary, lagged negative returns have a weaker influence on cash outflows from SR funds compared to the conventional counterpart.
We hypothesized a weaker influence of abiotic variables on forest structure where the intensity of the primary human disturbance factors, forest thinning and cattle grazing, had been strongest.
The background energy level which is determined by the backscatter efficiency and the lattice symmetry is shown to have a weaker influence on the maximum fill ratio.
During the LGM, SSTs were 3 °C cooler than today, and SSSs were almost the same or 1 psu saltier, which might indicate that the summer East Asian monsoon had a weaker influence than it does today.
Propionic acid degradation is largely inhibited during periods of high activity of the butyric acid-converting bacteria, whereas acetic acid exerts a weaker influence on the conversion of propionic acid [59].
As the article notes, gas prices do seem to exert a weak influence on voting behavior.
They found that physical activity does have a weak influence daily energy expenditure, but only among subjects on the lower half of the physical activity spectrum.
Servo voltage has a weak influence on average wire amplitude.
Interface style and perceived ease of use had a weak influence on perceived enjoyment.
The EPC was found to have a weak influence, especially pre-purchase.
