  We explore the potential of INTEGRAL to improve our understanding of the low
fluence regime for explosive transients, such as GRBs. We probe the nature of
the so-called "WEAK" INTEGRAL triggers, when the gamma-ray instruments record
intensity spikes that are below the usual STRONG significance thresholds. In a
targeted Swift follow-up campaign, we observed 15 WEAK triggers. We find six of
these can be classified as GRBs. This includes GRB150305A, a GRB discovered
from our campaign alone. We also identified a source coincident with one
trigger, IGRW151019, as a candidate AGN. We show that real events such as GRBs
exist within the IBAS WEAK trigger population. A comparison of the fluence
distributions of the full INTEGRAL IBAS and Swift BAT GRB samples showed that
the two are similar. We also find correlations between the prompt gamma-ray and
X-ray properties of the two samples, supporting previous investigations. We
find that both satellites reach similar, low fluence levels regularly, although
Swift is more sensitive to short, low fluence GRBs.
