Sometimes I lag and use same weapon twice in same round

It’s only happened during campaign. When it happens flash player lags as I’m telling it to use the first attack and then I’m able to attack with the same weapon again. Every time it’s happened it’s been with Stormweaver (energy axe) or Last Words. The fact that it lets me use Stormweaver again even when they’ve been knocked back to two range is also rather odd.