  The Weak Gravity Conjecture (WGC) is usually formulated in terms of the
stability of extremal black-holes or in terms of long distance Coulomb/Newton
potentials. However one can think of other physical processes to compare the
relative strength of gravity versus other forces. We argue for an alternative
formulation in terms of particle pair production at threshold or, equivalently,
pair annihilation at rest. Imposing that the production rate by any force
mediator (photon or scalar) of pairs of charged particles be larger or equal to
graviton production, we recover known conditions for the $U(1)$ WGC and its
extensions. Unlike other formulations though, threshold pair production is
sensitive to short range couplings present in scalar interactions and gives
rise to a Scalar WGC. Application to moduli scalars gives rise to specific
conditions on the trilinear and quartic couplings which involve first and
second derivatives of the WGC particle mass with respect to the moduli. Some
extremal solutions to these equations correspond to massive states behaving
like BPS, KK and winding states which feature duality invariance and are in
agreement with the Swampland distance conjecture. Conditions for $N=2$ BPS
states saturate our bounds and we discuss specific examples of BPS states which
become massless at large Kahler moduli in Type IIA N=2, D=4 CY and orbifold
compactifications. We study possible implications for potentials depending on
moduli only through WGC massive states. For some simple classes of potentials
one recovers constraints somewhat similar but not equivalent to a Swampland dS
conjecture.
