And doesn't Riot Blade lock weaponskills for 30seconds?
Um, I don't think it does. You just have zero TP after using it.

Is there even another weaponskill that's viable to use? The others seem kinda eh.
Spinstroke II is great when the mob is attacking someone else. Luminous spire is magic-based and never misses (At least, I've never once had it miss). Some people are into Onion cut, but it's always been Meh for me.

It is true that pretty much any other class who knows what they are doing will out-DOT a GLA, but perhaps unsurprisingly, many of these players are either lazy or don't know what they are doing... it's also a matter of two different things:

1, timing. The tank gets to smack the mob quite a bit on tough mobs before everyone else joins in. That damage counts to the overall total...

2, you don't have to let up, ever. Ever. Taking hate isn't a problem!

All I know is that in parties in beastman strongholds, I shouldn't be able to pull hate when I'm set up for DD and there are other DD's in the party, and I'm not using any enimity skills or Intimidation... yet it happens all the time. That means I'm out-damaging them in some way.