'weaker impact' is a perfectly correct phrase to use in written English.
You might use it in a sentence like this: "The new policy was met with a weaker impact than expected."
Connections with computer networks have a weaker impact.
But, after the storms swept through, their attitudes changed, especially if they had been personally affected by Hurricane Sandy; Irene, the weaker of the two storms, had a much weaker impact.
An outstanding feature of the Tunnel FET switch is that length scaling has a much weaker impact on device characteristics than does gate control (e.g. the use of a high-K dielectric), which primarily dictates the tunneling barrier width and consequently, device conduction.
Modern earthquakes are more frequent, smaller in magnitude, and have a weaker impact on the region.
By the same token, a frequently used metaphor can have the weaker impact of a simile.
Due to higher prices per ton kilometer, reclassifications have a relatively weaker impact on total costs in Europe.
The factors E (powder concentration) and H (powder size) are found to have relatively weaker impacts on the process design of the high-speed EDM.
As shown in Fig. 1b, the earthquake intensity peaked at the epicenter in Wenchuan and Lixian Counties, and gradually weaker impacts occurred up to about 200 km away.
Moreover, IDP mutations have weaker impacts on general protein protein interactions.
Alliaria petiolata individuals descended from older populations have been shown to exert weaker impacts on soil fungal communities (Lankau 2011b) and several tree species (Lankau et al. 2009).
In addition, the model is revised such that the reactions from Cdc20 and Clb2 make stronger and weaker impacts on Swi5, respectively.
