Is Geomancer too weak?

Bard offers incredibly strong buffs and has very powerful melee capability.

Cor is as above.

RDM has decent buffs and strong melee capability.

Geo has strong buffs and debuffs, however geo spells are locked position (meaning you have to drag monsters to it) and has next to no melee ability.

How about adding a job ability for geo that stops it being able to cast geo spells, but lowers the cooldown of entrust to 4 minutes.

This gives it a boost it needs for situations where it's not stuck to one camp.

It might be more interesting to have an effect which allows Entrust to be used five times in succession, but prevents self-targeted Indi- spells and any Geo- spells for a while. Entrust spells are weaker since they calculate potency based on the target's equipment rather than the caster's, so it would be trading two big effects for five small ones.

Geomancer's real problem, though, is it just... doesn't have a whole lot to do. It can use elemental magic, but not as well as Black Mage and Scholar. Free nuking just isn't a big thing these days, if you're casting you're expecting to magic burst... but the diminishing returns on magic bursts means you want to actively discourage any but your best caster from doing them. A job trait that prevents spells from counting toward the penalty on successive magic bursts might make Geomancer a more appealing option for fights which need more magic damage.

No melee ability????? I bring GEO/NIN to Sortie and crack some skulls!

No melee ability pre-Nyame. Everything's a semi-competent melee job with Nyame rank 25.