Guild Wars 2

It used to grant the effect on attunemant swap (counted as weapon swap)

now it doesn’t

Yes I was in combat.

I guess

If at any point you have two same Sigils equipped on a one weaponset, a stacking rule is applied. While rule is on, you need two same Sigils to get the effect. If you have only one Sigil then it has no effect. Rule is cleared when you have zero of that Sigil equipped.

This means that while equipping and unequipping, it is possible to mess up for example Sigil of Force and lose 5% damage.

Oh wow, thanks that actually worked. Was redoing my sigils and sets at that time, I probably equipped 2 of the same at one point.