Like others have said, you'll see it in your TP gain. But to see it, you need to know how weaponskills work.
For multi-hit skills, you get full TP for the first hit, and 1 TP for the other hits. If you're dual-wielding, it actually adds a fully-modified additional hit to your weaponskill, for which you get full TP for as well.
So, for example, for Dancing Edge (6 hits when dual-wielding):
First hit (5) + 1 + 1 + 1 + 1 + 5 (off-hand hit) = 14% TP gain for all hits.
Additional TP means you've double or triple attacked (if THF) for one or more of those hits.