Akaris / Akarius - I was able to find Acarius, which is [name_m]Roman[/name_m] in origin and the name of a saint and a bishop.
Glendonwyn - I couldn’t find this, but I found [name_m]Glendon[/name_m], from a place name in [name_u]Devon[/name_u] and Northamptonshire. It has Cornish and Old English roots and refers to a hill or valley clean of weeds. The -wyn suffix is Welsh from “gwyn” meaning “white.”
[name_m]Ninian[/name_m] - name of a 5th century British saint, derived from Nynniaw, a Welsh name of unknown meaning that was given to a prince who fought against the invasion of [name_m]Julius[/name_m] [name_m]Ceasar[/name_m]. Niniane is one of the names of the Lady of the [name_u]Lake[/name_u] in the Prose [name_m]Merlin[/name_m].
Albreda - a Medieval [name_m]German[/name_m] name, the feminine form of Alberich, meaning elf + power. Alberich was a sorcerer king of the dwarves in Germanic mythology.
Ranulf - This one is actually the Scottish version of Randulfr, the Old Norse form of [name_m]Randolf[/name_m]. It means rim (of a shield) + wolf.
[name_m]Bardolf[/name_m] - variant of Germanic [name_m]Bardolph[/name_m] meaning small ax or beard + wolf. Used in several of [name_m]Shakespeare[/name_m]'s works.
Æthelred - variant of Æðelræd, meaning noble counsel, the name of two [name_m]Saxon[/name_m] kings.
Æthelwulf - from Æðelwulf, the Old English cognate of the Germanic Adalwolf, now [name_m]Adolf[/name_m], meaning noble wolf. Understandably, this name is rarely used, though it was the name of several Swedish kings before Hitler ruined it for all of us.
Ætheling - the suffix -ling means “having to do with,” but I was unable to find this name. I would hazard a guess that it means little noble or something to that effect. The closest variant I found was Æthelwin, from Æðelwine, meaning noble friend.
Leofric - means “dear, agreeable, beloved” + power. This one is my favorite of your list!