Respecs are best if you want to completely reinvent your character. e.g., leveled an archer to 25, decided you can't stand it, go ahead and respec. If you just wish you had a couple more athletics or a couple more PS or something, go ahead and power through to 31 and retire. In My Opinion.
Regarding Ginosaji's comment, there are some 0 slot 1H weapons. So you could do:
Shield: 1 slot
Crossbow: 2 slots
Bolts: 1 slot
"Hammer" or "Hand Axe": 0 slots
Not that great because you have limited ammo and a crappy melee weapon. When I did archery with a longbow (2 slots), I skipped the shield. Bow, 2 quivers and a hammer and just tried to avoid melee.