[quote=Loremaster]
Dhalgren has quick draw so withdrawing the javelin should be a free action, holding the halberd (but not wielding) probably is a free action too, but I’d need to check, which I lack the time for now (similar to how mages with staffs can hold the weapon in one hand to cast a spell).
[/quote]

Most RAI opinions favor the free action to single hand. I don't know if RAW states anything on it, but anyone can hold a two-handed weapon in one hand to do something else like punch with a spiked gauntlet. (Most reach weapon wielders have a spiked gauntlet to use for adjacent combat.)